This is a case in which we need to decide whether to use the word "which" or "that" to introduce the clause set apart from the rest of the sentence by commas. "That" is used to introduce information absolutely necessary to the sentence's meaning, whereas "which" is used to introduce information that would not change the sentence's meaning if it were removed from the sentence. Information that is not crucial to the sentence's meaning is usually set apart by commas.

In this case, the sentence "The last time it snowed, my dad lost control of his car and hit a tree" still makes sense, so we know that the information included between the commas isn't absolutely necessary to the sentence's meaning. Plus, the information in question is being set apart from the rest of the sentence by commas. So, we should use "which," and not "that."

Because the second independent clause contradicts the first in this compound sentence it is more correct to separate the two with the conjunction "but," not "and."

Only answer choice "the heroine, Catherine, must choose between true love and social preeminence" correctly uses "and" with the preposition "between."

The other answer choices, including the original text "the heroine, Catherine, must choose between true love or social preeminence," contain an incorrect idiomatic expression. When we have "between," we typically need the word "and"—rather than "or"—to separate the entities that follow.

In standard English, when you use the phrase "not only" in a sentence, it should be followed by the phrase "but also." So, the correct answer is "When she went to the zoo, Lyndsey got to see not only tigers, but also polar bears, iguanas, and toucans."

When "neither" is used in a sentence, "nor" should follow it, creating the structure "neither X nor Y," where X and Y are items formatted in the same manner. To correct the sentence, we need to change "and definitely not" to "nor." Several answer choices do this: "nor faithful to the original film," "nor were it faithful to the original film," and "nor was it faithful to the original film." "Nor were it faithful to the original film" and "nor was it faithful to the original film" might each look like potentially correct answers, but each introduces a verb that disrupts the parallel structure of "neither X nor Y," in which "nor" should be immediately followed by "faithful to the original film." The correct answer is thus "nor faithful to the original film," making the corrected sentence, "The remake of the film was neither enjoyable nor faithful to the original film."

The best way to rephrase "help treat, but even help prevent, most psychological disorders" is "help treat and even prevent most psychological disorders." Commas can be used to denote an interrupting phrase, which is an idea connected to the main idea but not necessary to the understanding of the main idea of the sentence. For example, an interrupting clause may provide additional information about the main idea or a qualification (using "but" or "however"). In this example, the idea that psychotherapy can help prevent psychological disorders is part of the main idea of the sentence, so it does not have to be separated from the remainder of the sentence by commas.

The correct form for this sentence is "neither . . . nor." In addition, "neither . . .nor" leads to use of the singular form "is" rather than "are."

The comma is excessive and causes problems with the logic of the sentence. “Which” usually requires a comma before it and follows a fact, assertion, or statement. The sentence's use of "which" doesn't come after a comma, so it should be changed to "that."

This sentence requires use of “that” because the United States is a country (e.g., a noun). Also, “British” must be capitalized because it is a nationality. 

The sentence is trying to explain that in spite of the giant squid's elusiveness, scientists are finding new ways of studying it. The sentence therefore is trying to contrast two ideas, as opposed to showing causation with the word "because." The only answer choice that uses a contrasting conjunction is "Although," so it is the correct answer.