Change the sentence from affirmative to negative :- 1. You are richer than me.
2. She tried all plans.
3. A few farmers saved their crop.

A negative sentence has a negative word like 'no', 'not', 'never' along with the verb. Alternately, it has a negative noun like 'nobody' or 'nothing'. An affirmative sentence has no negative word in it.
Option A: This is an affirmative sentence. This sentence conveys the same meaning as the original sentence. Hence, this option is correct.
Option B: This is a negative sentence as it contains the words, 'not' in it. Hence, this option is incorrect.
Option C: This is an affirmative sentence. However, its meaning is different from that of the original sentence. Hence, this option is incorrect.
Option D is incorrect as option A is the correct answer.