First important thing to notice is that RNA doesn't have Thymine, all thymines are changed for Uracils. Then, the correspondency is thymine-Adenine, Guanine-Cytosine (and viceversa) Adenine-Uracil. Lastly, the transcription process happens from 3' to 5', so the question asks for the final result to be read to the opposite direction. Therefore, the correct answer is C.
Nitrogen must be converted into nitrates before organisms can use it. If soil lacks nitrogen fixing bacteria, then it has few nitrates for the plants to take in.
