The sentence describes what humans did to horses in the past, a fact that needs to be reflected in the verb's tense and transitivity. The correct answer must indicate that the domesticating being discussed took place in the past and was done by humans to horses, leading to "were domesticated" as the only possible answer choice.

This sentence contains an error in verb voice. The phrase "His pictures were hung" is in the passive voice. The correct choice should always be in the active voice (i.e. the subject of the sentence should be doing the action of the main verb). No other changes are necessary. The correct choice is "He hung his pictures on the wall in order to show off."

This sentence contains an error in verb voice. The phrase "Kim was praised" is in the passive voice. The correct choice should always be in the active voice (the subject of the sentence should do the action of the sentence). The correct choice is, "Kim's teammates praised her for scoring the winning goal at the last second."

This sentence contains an error in verb voice. The phrase "The video games are played" is in the passive voice. The correct choice should always be in the active voice (the subject of the sentence should do the action of the sentence). The correct choice is, "The programmers play the video games daily to test for bugs in the system."

This sentence contains an error in verb voice. The phrase "The band's music was acclaimed" is in the passive voice. The correct choice should always be in the active voice (i.e. the subject of the sentence should be doing the action of the main verb). No other changes are necessary. The correct choice is, "Many people thought the band's music was innovative and thrilling."

This sentence contains an error in verb voice. The phrase "her work was considered to be the best" is in the passive voice. The correct answer should be in the active voice (i.e. the subject of the clause should always be doing the action of the main verb). No other changes are necessary. The choice that fixes this issue is, "influence in her field since people considered her work the best."

This sentence contains an error in verb voice. The phrase "Roger was asked" is in the passive voice. The correct choice will usually be in the active voice (i.e. the subject of the clause should be doing the action of the main verb). No other changes are necessary. The correct choice is, "They asked Roger to come into the office."

This sentence contains an error in verb voice. The phrase "a new book from her favorite author was being published later this year" is in the passive voice. The correct choice will always be in the active voice, so this sentence needs to be rephrased. The correct choice is, "her favorite author was publishing a new book later this year."

This sentence contains an error in verb voice. The phrase "Conventions...are attended" is in the passive voice. The correct choice should always be in the active voice (i.e. the subject of the clause should be doing the action of the main verb). The correct choice is, "Millions attend conventions for anything imaginable."

This sentence contains an error in verb voice. The phrase "the technology was improved" is in the passive voice. The correct choice should always be in the active voice (i.e. the subject of the clause should always do the action of the main verb). This can be fixed by simply omitting the word "was." No other changes are necessary. The correct answer is, "Because the technology improved."