This sentence misuses an apostrophe. Apostrophes should never be used to pluralize a noun. The correct plural of "stock" is "stocks." The correct answer choice is, "people invest in stocks."

This sentence contains an apostrophe error. The word "bags" is possessive in this sentence; in order to make it properly possessive, an apostrophe is needed before the "s." No additional punctuation or changes are necessary. The correct choice is, "The book bag's weight was."

This sentence misuses an apostrophe. The word "it's" is a contraction for "it is." The correct word is "its," without the apostrophe, which is the possessive form of "it." No other corrections are necessary. The other choices are wrong because of other small errors in noun-adjective agreement or punctuation. The correct choice is, "Because of its constant malfunctions, the owner."

This sentence misuses an apostrophe. It is clear from the context of the sentence that the sentence is referring to many students (they key word is "them"). The correct plural, possessive form of the word "student" is students'. No other changes are necessary. The correct choice is, "The teacher collected the students' homework every day."

This sentence misuses the word "its'." In fact, "its' " is not a word at all. What is necessary in this spot is the possessive form of "it," which is "its (no apostrophe)." No other changes are necessary. The correct choice is, "gave its employees particularly big bonuses this year."

This sentence misuses an apostrophe. The word "coworkers" in this sentence is clearly meant to be plural; words should never be pluralized with an " 's." The correct choice is, "speak with his coworkers every day."

This sentence misuses an apostrophe. While the latter half of the sentence contains a possessive statement ("their food"), the word "rabbits" is not possessive itself, but plural. An apostrophe should never be used to pluralize a word in English. The correct choice is, "The rabbits ate their food."

This sentence contains an error in the placement of the apostrophe. The word "investors" is plural, which we can deduce by the use of the pronoun "their" later on in the sentence. The correct possessive plural contains an apostrophe after the "s." The correct choice is, "The investors' opinions on the company greatly influenced."

This sentence misuses an apostrophe. It is clear from the context that the word "company" should be plural; however, you should never use an " 's" in order to pluralize a word. The correct plural form of "company" is "companies." The correct choice is, "the companies nearby, she was unable to interest them."

This sentence contains an error in the use of the apostrophe. Even though the word "his" is possessive, it is possessive already without the need for an " 's." Omit the apostrophe; the correct choice is, "His sister said she would visit."