Which of the two dna strands serves as the template for transcription?
a. either dna strand may be used as a template by rna polymerase, but a single dna strand oriented in the 3'–5' direction is used as a template each time transcription occurs.
b. the dna strand oriented in the 5'–3' direction is the only template because only this strand contains the polymerase binding sequences necessary to initiate transcription.
c. the dna strand oriented in the 5'–3' direction is the only template because rna polymerase synthesizes only in the 5'–3' direction.
d. both dna strands serve as templates simultaneously for rna polymerase, with continuous transcription on the leading strand and discontinuous transcription on the lagging strand.