Explanation
Correct answer: B.
Choice B is the best answer. The convention being tested is the use of verbs to express tense in a sentence. In this choice, the past tense verb “vowed” is consistent with the other past tense verbs (“guided” and “upheld”) used to narrate the events surrounding President Roosevelt’s decision to conserve the nation’s wilderness areas.
Why the other choices are wrong
Choice A
Choice A is incorrect because the present progressive tense verb “is vowing” isn’t consistent with the past tense verbs used to narrate the events surrounding President Roosevelt’s decision to conserve the nation’s wilderness areas.
Choice C
Choice C is incorrect because the future tense verb “will vow” isn’t consistent with the past tense verbs used to narrate the events surrounding President Roosevelt’s decision to conserve the nation’s wilderness areas.
Choice D
Choice D is incorrect because the simple present tense verb “vows” isn’t consistent with the past tense verbs used to narrate the events surrounding President Roosevelt’s decision to conserve the nation’s wilderness areas.