This sentence uses “that” to introduce a non-restrictive clause (added information rather than details central to the meaning of the sentence). It would be correct to use “which” instead: "Before she traveled to Peru, she decided to start learning Quechua, which is one of the most popular local languages."

This sentence is not coordinated correctly. When the first phrase starts with “although,” the main phrase should start after the comma without using another conjunction in between the comma and the main phrase. The corrected sentence reads, "Although the popular image of a Viking is a large man with horns on his helmet, there is no evidence that Vikings actually wore horns."

The conjunction used in this sentence (“and”) does not match the logic of the sentence's content. The two parts oppose each other, so “but” is more appropriate. The corrected sentence reads, "Traveling during the holidays can be expensive, but it is worth it to celebrate with your family."

The conjunction that this sentence uses does not make logical sense. The first half is the reasoning for the second half, so the conjunction “so” would be more appropriate. The corrected sentence reads, "The weather should be beautiful on Friday, so Barbara has made plans to go hiking."

This sentence contains a redundancy error. The conjunctions "but" and "yet" are synonyms; they mean the same thing, so only one or the other is necessary to convey the intended meaning of the sentence.

The answer choice "sold" is correct because it contains the simple past tense, which is correct for events that happened in the past and don't continue into the present.

The answer choice "greatest" is correct because it uses the superlative form (the "-est" form) of the adjective great, which is appropriate for comparisons involving more than two items.

The answer choice "of all time" is a perfectly correct use of an idiomatic expression.

This sentence has a clunky dependent clause tacked on the end. We can make it sound better by taking out some words and making it an appositive phrase: "Defying all expectations, the space shuttle reentered the atmosphere at 3:57, three whole minutes ahead of schedule." Or, alternatively, one could also change "that was" to "which was," but one introduce a phrase that provides additional information about a subject and follows a comma with "that"; one should use "which" instead in this instance.

This sentence contains a logical error. The long line was the cause of missing the start of the movie, so the use of a contrasting conjunction like "although" here is wrong. Replacing it with "Because" or "Since" would be a simple correction.