Which sentence uses prepositional phrases to convey meaning?

What is the authors purpose in writing this paragraph

Writers can create sound effects in poetry by utilizing sound devices. a dictionary. mnemonic devices. capitalization.

Which sentence from a student's reflective essay contains a subject and verb error and needs to be edited? a. in my opinion, some of the voters seemed to need more information about their candidates. b. the documentary showed that dollars are often used instead of rubles in russia. c. the research shows that jackets made of wool are warmer than those made of cotton. d. in my opinion, either the doctors or the chief administrator need to make a quick decision.