In 1943, Maria Telkes created the first house fully heated by solar power. Her detailed plans showing how solar energy could be used and her process of running tests to see if the system could work without failure helped change the traditionally fossil fuel-dependent ways of heating toward a green one.Choice D is the best answer. The convention being tested is fragmentation, which refers to a group of words that is not a complete sentence but is punctuated as one. A complete sentence requires at least a subject and a verb, and this choice supplies the clause with the past tense verb “helped” to perform the action of the subject “her detailed plans … and her process of running tests.”
Choice A: “To help” is a to-infinitive and therefore cannot serve as the main verb of the sentence.
Choice B: “That helped” is a relative clause and therefore cannot serve as the main verb of the sentence.
Choice C: “Helping” is a present participle and therefore cannot serve as the main verb of the sentence.
✨ Expert's Tip ✨
In order for a group of words to constitute a complete sentence, it must have a subject and a verb. Otherwise, it is a sentence fragment.