Question

what do plants produce using nitrogen?
a. sugar
c. protein
b. nitrogen oxides
d. fat

Explanation:

Plants absorb nitrogen (e.g., as nitrate) to synthesize molecules containing nitrogen. Proteins are composed of amino acids, which have nitrogen in their amino groups ($-NH_2$). Sugars (A) and fats (D) consist of only C, H, O; nitrogen oxides (B) are not plant products. Thus, proteins require nitrogen.

Answer:

C. Protein