The correct answer is: D. Tea grows in Darjeeling.
The other options are incorrect because they do not accurately reflect the tense of the sentence. Option A, “Tea is being grown in Darjeeling,” is in the present progressive tense, which indicates that the action of growing tea is ongoing. Option B, “Let the tea be grown in Darjeeling,” is in the imperative mood, which indicates that the speaker is giving a command or making a request. Option C, “Tea is grown in Darjeeling,” is in the simple past tense, which indicates that the action of growing tea was completed at a specific time in the past.
The sentence “Darjeeling grows tea” is in the simple present tense, which indicates that the action of growing tea is a regular or habitual occurrence. This is consistent with the fact that Darjeeling is a region in India that is known for its tea production.