Explanation
Correct answer: C.
Choice C is the best answer. The convention being tested is the use of verbs to express tense in a sentence. In this choice, the present perfect tense verb “have contributed,” used in conjunction with the phrase “since it began in 2012,” correctly indicates that map editors have contributed in the past and continue to do so in the present.
Why the other choices are wrong
Choice A
Choice A is incorrect because the present tense verb “contribute” is inconsistent with the phrase “since it began in 2012,” which suggests that the contributions occurred in the past and continue into the present.
Choice B
Choice B is incorrect because the future tense verb “will contribute” is inconsistent with the phrase “since it began in 2012,” which suggests that the contributions occurred in the past and continue into the present.
Choice D
Choice D is incorrect because the future tense verb “will be contributing” is inconsistent with the phrase “since it began in 2012,” which suggests that the contributions occurred in the past and continue into the present.