Question 200·Medium·Form, Structure, and Sense
Popular science podcasts, which feature interviews with leading researchers as well as lively discussions of recent discoveries, ______ quickly becoming a primary source of information for listeners who prefer audio content to traditional print articles.
Which choice completes the text so that it conforms to the conventions of Standard English?
For subject–verb agreement questions, first strip away any extra phrases set off by commas or dashes to find the core subject and verb. Decide whether the subject is singular or plural, then look at context words (like "now," "currently," or an "-ing" verb) to determine the tense. Finally, eliminate choices that either disagree in number with the subject or don’t match the time frame or structure implied by the rest of the sentence.
Hints
Locate the core sentence
Ignore the information between the commas (the part starting with "which") and find the main subject and verb of the sentence.
Check singular vs. plural
Ask yourself: Is "Popular science podcasts" referring to one thing or more than one thing? Your verb must match that number.
Think about time and action
Does the sentence describe something that happened in the past, or a change that is happening now? Focus on the word "becoming" to help you decide.
Match the helping verb to "becoming"
You need a form of "to be" that correctly combines with "becoming" and agrees with a plural subject in the right time frame.
Step-by-step Explanation
Find the main subject of the sentence
Ignore the information between the commas (the nonessential clause) and focus on the core sentence structure:
"Popular science podcasts ... ______ quickly becoming a primary source of information..."
The main subject is "Popular science podcasts." This subject is plural (it refers to more than one podcast).
Decide what tense and form the verb should have
The phrase "quickly becoming" shows an action that is happening now and is in progress. That is the present progressive tense ("are becoming"/"is becoming").
So we need a form of the verb "to be" that:
- Works with "becoming" to form a progressive tense, and
- Matches a plural subject in present time.
Match the subject and tense to the answer choices
Check each option against what we need (plural, present, and working with "becoming"):
- A present-tense singular verb would not match a plural subject.
- A past-tense verb would not match the "quickly becoming" idea of a current trend.
- A present perfect progressive form must agree in number and also fit the time frame of the sentence.
Only one choice both agrees with the plural subject and correctly matches the present progressive meaning.
Choose the verb that fits
Because "Popular science podcasts" is plural and the sentence describes a current, ongoing trend, the correct verb is the present plural form "are":
"Popular science podcasts ... are quickly becoming a primary source of information..."