Whole wheat flour has an extraction rate of:

Correct option is A

Extraction rate refers to the percentage of flour obtained after milling wheat relative to the original grain weight.
Whole wheat flour contains all parts of the grain—bran, germ, and endosperm—thus the extraction rate is 100%.
Other flours:
85% extraction: High-extraction wheat flour, with some bran/germ removed.
72–76% extraction: Refined white flour (maida), primarily consisting of endosperm with bran and germ removed.
Therefore, whole wheat flour = 100% extraction rate, making the correct answer Option (a).