Which choice completes the text so that it conforms to the conventions of Standard English?
A
have been powering
B
power
C
powers
D
are powering
Explanation
Correct answer: C.
Choice C is the best answer. The convention being tested is subject-verb agreement. The singular verb "powers" agrees in number with the singular subject "an artificial intelligence."
Why the other choices are wrong
Choice A
Choice A is incorrect because the plural verb "have been powering" doesn’t agree in number with the singular subject "an artificial intelligence."
Choice B
Choice B is incorrect because the plural verb "power" doesn’t agree in number with the singular subject "an artificial intelligence."
Choice D
Choice D is incorrect because the plural verb "are powering" doesn’t agree in number with the singular subject "an artificial intelligence."