During the nitrogen cycle, plants take in nitrogen compounds through their

Root nodules is the correct answer of this question.

Explanation:

Root nodules and nitrogen is absorbed by soil which is then absorbed by plants roots Nitrogen is a central component of living organisms ' bodies. All proteins contain nitrogen atoms, and \text{DNA}DNA start text, D, N, A, end text.Root nodules are located at plant roots, mainly legumes, which form a symbiosis of nitrogen-fixing bacteria.Plants take a nitrogen compounds through root nodules.

The correct answer is b

Active site is where they touch.