The Heinz Dilemma refers to a story used by Kohlberg in his study on moral development about a man who steals drugs to help his wife who is dying of cancer. By asking how people would react to this dilemma, Kohlberg developed his stages of moral development which correspond more or less to peoples' age groups.

Pre-conventional morality is most common amongst infants or toddlers whose primary focus is to avoid punishment and seek reward. Consequently, any morals they have will be based on that principle.

Kohlberg's stages of moral development were based on Jean Piaget's stages of childhood development. Kohlberg's first stage is the Pre-Conventional, which consists of obedience orientation (punishment avoidance) and self-interest orientation. The second stage is the Conventional, which consists of interpersonal conformity to social norms and authority orientation. The third and final stage is the Post-Conventional, which consists of universal ethical principles (conscience) and social contract thinking.

Kohlberg's three levels of moral thinking include preconventional, conventional, and postconventional. 

From birth to about nine years of age, a child is believed to experience what Kohlberg called the preconventional phase. At this time the focus is self-interest; the child will follow rules just to avoid punishment and achieve a concrete reward. 

The other two options, “preoperational” and “concrete operational” are incorrect because they are stages from Piaget's theory of cognitive development. 

Kohlberg's three levels of moral thinking include preconventional, conventional, and postconventional. 

From adolescence and beyond, Kohlberg believed that an individual experiences the postconventional level of morality. During this time, the individual focuses on actions that demonstrate a belief in self-defined ethical principles and basic rights. 

“Ego” would be incorrect as it is one of Freud's psychoanalytical stages.

“Concrete operational” would also be incorrect because it is one of Piaget's stages from his theory of cognitive development. 

Kohlberg’s model of moral thought was categorized into three levels: pre-conventional, conventional, and post-conventional. Pre-conventional moral thought is concerned with thoughts associated with obedience, punishment, and self interests (e.g. “if I steal, then I will be caught and punished” and “stealing is against the law”). On the other hand, post-conventional thought is characterized by higher order moral thinking such as that associated with social contracts and universal ethical principles. Last, the conventional level is characterized by thoughts indicative of social order and conformity (e.g. the correct answer “if I steal, then people will think I’m a bad boy”).

The conventional stage of moral development occurs from approximately 10 years old to early adolescence. During this stage, children make decisions based on how the world will view them. Children learn conventional standards of right and wrong, as usually follow these so others will see them as "good." 

Kohlberg's theory of moral development divides morality into three levels: preconventional, conventional, and postconventional. The preconventional level occurs prior to age 10 and involves a desire to avoid punishment and receive rewards. Children in this stage may follow rules because of their own self-interests. Children in the conventional stage are motivated to do what is right and uphold society's rules and standards. This is consistent with Mark's philosophy on why lying is wrong. During the postconventional stage, people develop an internal set of values and have a more flexible view of morality. Kohlberg believed that not everyone reaches the postconventional level. The oral and latency stages are associated with Freud's psychosexual stages of development. 

Lawrence Kohlberg believed that there are three different stages of morality that are expressed through our actions. The young child above is engaging in "pre-conventional morality." In this stage, actions are determined to be bad or good depending on how they are rewarded or punished. Specifically, the action of stealing is determined to be bad because society has set forth rules that would likely result in the young child getting punished for it.  

The conventional stages of Kohlberg's stages of moral development are associated with morality derived from "social norms and expectations." This is in contrast with the pre-conventional stages, which focus on self-interest and punishment, and the post-conventional stages, which focus on social contracts and universal principles.