This sentence misuses a comma. The phrase "Because of farming and herding" is an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. A comma is not necessary, however, before the "and," because the phrase "farming and herding" is not a list (a list contains three or more items), and it is not combining independent clauses. The correct choice is, "Because of farming and herding, humans are able."

This sentence does not contain commas where necessary. The phrase "one of the top schools in the United States" is an example of a relative clause, which gives more information about its antecedent: Harvard. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct choice is, "Harvard, one of the top schools in the United States, has an endowment worth billions of dollars."

This sentence contains an error in the placement of the comma. There is no need for a comma to come after the word "during," since it is not the end of the phrase. The phrase "During his flight" is an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "During his flight, Hector was able to catch."

This sentence misuses a comma. The phrase "Otto and his brother" is part of the same clause: it is not a list (3+ items), two clauses, or anything else that would reason the use of a comma. This is a simple sentence, so no punctuation is necessary. The correct choice is, "Otto and his brother went to the park every Saturday."

This sentence misuses a comma. There is no need for a comma before the word "or" because it is not joining two independent clauses together. This is the only time you see a comma before a conjunction. The correct choice is, "whether he should pay his bills now or later."

This sentence does not contain commas where necessary. The phrase "which was to run her own bakery" is a relative clause, which gives more information about its antecedent: dream. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct answer choice is, "Cassandra's dream, which was to run her own bakery, seemed like."

This sentence misuses a comma. The sentence combines two independent clauses without the use of a conjunction. When this occurs, a semicolon is the appropriate punctuation mark: a semicolon should appear after the word "perfectionist." The correct choice is, "Jake was a perfectionist; it always bothered him when others." Note that the choice with the period is incorrect because "it" is not capitalized. 

This sentence omits commas where necessary. The phrase "the low overhead costs, exposure to many markets, and its ease to set up" is a list. All items in any sort of list/parallel words or phrases should be separated by commas. Additionally, a comma must come before the "and" because exposure to markets is not related to ease in setting something up, besides being another one of Dante's reasons. The correct answer is, "e-business because of the low overhead costs, exposure to many markets, and its ease to set up."

This sentence does not contain a comma where necessary. The phrase "books, maps, and other study materials" are all a part of the list, so a comma should appear after each item. Note that the comma before the "and" cannot be omitted because "maps" is not necessarily related to "other study materials." The correct choice is, "was filled with books, maps, and other study materials."

This sentence contains a comma where one is not necessary. Commas should only come before conjunctions when the conjunction joins two independent clauses. While "Sandra did not like beef" is an independent clause, "loved chicken" is not. The comma should be omitted. The answer is, "did not like beef but loved chicken."