DNA Strands in Transcription Steps:

• Identify the template strand as the one read by RNA polymerase during transcription to produce complementary mRNA.
• Note that mRNA base pairs with the template: A-U, T-A, G-C, C-G (DNA T becomes A in mRNA, etc.).
• Recognize the non-template strand has the same sequence as mRNA, except T in DNA vs. U in RNA.
• Compare each option to these base-pairing rules and sequence matches.

Why D is correct:

• By base-pairing rules in transcription, the template strand's sequence is complementary to the mRNA, which is then used in translation.

Why the others are wrong:

• A: Non-transcribed (non-template) strand matches mRNA sequence but is not identical due to T in DNA vs. U in RNA.
• B: Template strand is complementary to mRNA, not identical.
• C: Non-template strand matches mRNA sequence, not complementary to it.

Final answer: D