There are many types of forces, but our answer choices include four types. In order to answer this question correctly, we need to be able to decipher between them. 

Applied force is a force that is applied by a person to an object. 

Gravity force is also known as the weight of the object. It's the force that allows a large object to attract another object towards itself.

Normal force is also known as supportive force. It is the force exerted upon an object that is in contact with another object, one object holds the other up. 

Friction force is the force exerted by a surface as an object tries to moves across the surface.

Let's think about the scenario from the question. What causes a person to be kept on the ground, rather than floating around? Gravity forces us towards the ground; thus, gravity force is the correct answer. 

There are many types of forces, but our answer choices include four types. In order to answer this question correctly, we need to be able to decipher between them. 

Applied force is a force that is applied by a person to an object. 

Gravity force is also known as the weight of the object. It's the force that allows a large object to attract another object towards itself.

Normal force is also known as supportive force. It is the force exerted upon an object that is in contact with another object, one object holds the other up. 

Friction force is the force exerted by a surface as an object tries to moves across the surface.

Let's think about the scenario from the question. A plate is sitting on the table, they are in contact with one another and the table is keeping the plate from falling to the ground; thus, this is an example of normal force. 

There are many types of forces, but our answer choices include four types. In order to answer this question correctly, we need to be able to decipher between them. 

Applied force is a force that is applied by a person to an object. 

Gravity force is also known as the weight of the object. It's the force that allows a large object to attract another object towards itself.

Normal force is also known as supportive force. It is the force exerted upon an object that is in contact with another object, one object holds the other up. 

Friction force is the force exerted by a surface as an object tries to moves across the surface.

Let's think about the scenario from the question. We have a marble, an object, that is rolling across the floor, which is a surface. Based on the definitions of the types of forces above, friction force is the correct answer. 

There are many types of forces, but our answer choices include four types. In order to answer this question correctly, we need to be able to decipher between them. 

Applied force is a force that is applied by a person to an object. 

Gravity force is also known as the weight of the object. It's the force that allows a large object to attract another object towards itself.

Normal force is also known as supportive force. It is the force exerted upon an object that is in contact with another object, one object holds the other up. 

Friction force is the force exerted by a surface as an object tries to moves across the surface.

Let's think about the scenario from the question. We have a student pushing a desk, which is an object, across the room. The student would have to apply some force to get the desk to move. Looking at the types of forces above, applied force fits this scenario best.