Although there are seven gems, the subject of the sentence is "Each" of the gems, which is a singular noun. Therefore, the correct phrase uses the singular past verb form—"was mined from each of the seven continents on Earth."

The singular use of "is going to" is correct, not the plural use of "are going to." This is because the verb "is" is modifying the "one" team that is going to make it, not the plural "teams." The "of the teams" can be taken out to show that one should use "is", not "are": "Only one . . . is going to make it to regionals."

The subject of this sentence, "A combination," is singular, so the predicate should be singular, too. The original text "delightfully entertaining plot twists characterize the novels of Jane Austen" and the answer choice "delightfully entertaining plot twists have characterized the novels of Jane Austen" contain plural predicates and therefore lead to subject-verb agreement errors. 

The answer choice "the fact that she twists the plot in delightfully entertaining ways characterizes the novels of Jane Austen" leads to faulty parallelism and the use of an ambiguous pronoun, and the answer choice "the fact that she twists the plot in delightfully entertaining ways characterize the novels of Jane Austen" leads to errors in both parallelism and subject-verb agreement.

Only answer choice "delightfully entertaining plot twists characterizes the novels of Jane Austen" correctly preserves the parallel structure and avoids any subject-verb agreement errors.

The use of the past tense verb "were" indicates that the main verb of the sentence, "knows," should also be in the past tense, as they should be in agreement. Thus, the verb "knows" needs to be changed to its past-tense form. "No one knew where the paintings" is the only answer choice that correctly does this.

The subject of the sentence is actually the gerund phrase "Making up stories," which is a singular construction, despite the use of "stories." The verb, therefore, must match the singular subject, but is written in a plural form. "Making up stories is one of the chief ways" is the answer choice that best corrects this issue.

The answer choice "argue that a feeling of connectedness with other human beings, along with a positive self-image, contributes to the overall health" is correct. It contains the correct number agreement of the verb "contributes" with its subject, "a feeling of connectedness with other human beings."

The answer choices containing "contribute" instead of "contributes" are incorrect. The subject of "contribute" is singular, not plural.

Although the answer choice "argues that a feeling of connectedness with other human beings, along with a positive self-image, contributes to the overall health" correctly contains "contributes," the verb "argues" introduces a number agreement error, as "argues" is singular but being used with a plural subject, "Freud and other advocates of introspective psychology."

The use of "all" is the key indicator of the correct answer in the sentence. While "Tom, Dick, and Harry" are singular as individuals, they are "all" together sharing their feeling as a plural group; therefore, "all lament" is the correct choice among the answers.

The underlined portion does not show proper subject-verb agreement. Although there are "children" playing, the sentence refers to "each," which is singular. "Each of the children is" is the correct answer.

In the original sentence, the noun "water bottle" is singular but the verb "were" is plural. Changing the noun to "water bottles" corrects this.

Although "pockets" may seem like the subject--which would make the original verb agree--"pockets" is actually an object of the preposition "of." So the verb "make" needs to be adjusted to "makes" in order to agree with the actual subject "Lint."