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."

This sentence misuses the commas in this sentence. When the word "that" is used, what would be a relative clause becomes part of the main clause, therefore making commas inappropriate, as it no longer separates anything. "Which" would be an appropriate choice, but only if both commas are there: none of the options offer this choice. The best choice is, "inventions that we use every day had their start."

This sentence misuses a comma. The word "since" is being used as a preposition in this sentence and does not begin a new clause. Commas are generally used to separate items and clauses from one another; it does none of these things in this sentence. The comma should be omitted. The correct choice is, "extracurricular activities since he was a kid," as this is a simple sentence.

This sentence does not contain a comma where one is necessary. The phrase "While looking through the company's books" is an example of 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, "the company's books, the accountant found many errors."