This sentence misuses the pronoun "who's." This word is a contraction for "who is." The appropriate form is "whose." The correct choice is, "Whose wallet is this?" The other choices contain errors in pronoun usage and dangling prepositions.

This sentence contains two pronoun errors. First, "who" is not the appropriate pronoun because it refers to "product," which is a non-human noun. All non-humans are referred to with the pronoun "which" in English. Furthermore, the usage of "they" is incorrect, since it refers to the word "company," which is grammatically singular, even though it possibly refers to many individuals. The correct choice is, "The company planned to dominate the market with its new product, which it nicknamed "Project Zero." "

This sentence misuses the pronoun "whose," which is possessive. It is clear from the context of the sentence that "who was" should be in this place. The correct choice is, "to determine who was responsible for the accident." Note that the choices with "he was" and "what person was" are wrong because the first is imprecise and ambiguous (it is typical to mention a person or thing by name before using he, she, or it) while the second is less concise.

The sentence presented uses a reflexive pronoun, "myself," that does not refer back to anything previously mentioned. The proper form would be the standard pronoun "me," which is the correct answer.

This sentence uses the wrong pronoun. Since the subject of the sentence is "services," the correct pronoun to describe it would be "they." The correct phrasing would be "they have," which makes the best choice: "but they have played an important role."

This sentence contains an error in pronoun usage. The pronoun "they" does not properly match its antecedent: a long-distance call. The usage of the article "a" indicates that "long-distance call" is singular (because it is referring to the general concept, not individual calls). Therefore, the appropriate pronoun would be "it." Furthermore, the change from "they" to "it" requires the verb to be changed as well from "are" to "is." 

The sentence joins two independent clauses together without the use of a coordinate conjunction, so the semicolon is necessary before the word "now," and the word "now" functions as an introductory phrase here, 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, "a long-distance call was a call to another city; now, it is more commonly a call."

This sentence uses the incorrect form of "who." "Who's" is a contraction for "who is." The appropriate form here is whose, which is the possessive form of the word "who." The correct choice is, "to know whose letter she received."

This sentence misuses the word "who." The pronoun "who" is reserved for humans only. All other things, whether living or not, is referred to as "which" in standard English. Note that "that" is inappropriate here because it would make the following phrase ("the company built") a part of the main clause, which would mean you would have to omit the commas. The same explanation applies to just omitting the pronoun. The correct choice is, "The robot, which the company built, was the first."

This sentence misuses the pronoun "who's." There are two issues with the usage of this word: first, "who's" is a contraction for "who is" and is not possessive; the correct form would be "whose." The second issue, however, is that "who" should never be used with non-human words. The correct pronoun would be "which." "That" cannot be used because it would make the phrase "has products I love" a part of the main clause, which would require deleting the commas. The correct choice is, "which has products I love."

This sentence misuses the pronoun "who's," which is a contraction for "who is." It is clear from the context of this sentence that the possessive form, "whose," is necessary here. The other choice are not actual forms of this pronoun or are too wordy. The correct answer is, "whose."