The correct answer is: C. learns
The sentence is in the present tense, and the subject is “nobody.” The verb “learns” is the only option that agrees with both the tense and the subject.
The other options are incorrect because they do not agree with the tense or the subject. Option A, “don’t learn,” is in the negative form, but the sentence is not negative. Option B, “are learning,” is in the present progressive tense, but the sentence is in the present tense. Option D, “doesn’t learns,” is not a standard English word.