On sunny days, dark rooftops absorb solar energy and convert it to unwanted heat, raising the surrounding air ______ blank

Question

On sunny days, dark rooftops absorb solar energy and convert it to unwanted heat, raising the surrounding air blank a light-colored covering to an existing dark roof, either by attaching prefabried reflective sheets or spraying on a paint-like coating, helps combat this effect.

Which choice completes the text so that it conforms to the conventions of Standard English?

Accepted Answer

Choice C is the best answer. The convention being tested is punctuation use between sentences. In this choice, the period is used correctly to mark the boundary between the first sentence (&ldquo;On...temperature&rdquo;) and the second sentence (&ldquo;Adding...effect&rdquo;). The gerund phrase beginning with &ldquo;adding&rdquo; is the subject of the second sentence, and the verb phrase &ldquo;helps combat this effect&rdquo; describes what adding a light-colored covering can do. Choice A is incorrect because a semicolon can&rsquo;t be used in this way to join the sentence &ldquo;On...temperature&rdquo; and the supplementary phrases that follow. Doing so leaves the verb phrase &ldquo;helps combat&rdquo; without a subject and thus results in a grammatically unconventional sentence. Choice B is incorrect because it results in a comma splice. A comma can&rsquo;t be used in this way to mark the boundary between sentences. Choice D is incorrect. This choice results in a confusing and illogical sentence that suggests that adding a light-colored covering to an existing dark roof raises the temperature of the surrounding air. Furthermore, it creates ambiguity by leaving the verb phrase &ldquo;helps combat&rdquo; without a subject (so it isn&rsquo;t clear what helps combat the effect).

Question a168e3