The picture below shows the process of transcription.

During transcription, enzymes bind to a molecule of DNA. Then, the enzymes unwind and separate the DNA's double helical strands. As the molecule unwinds, complementary nucleotides pair with one of the DNA strands to form
A.
an identical strand of DNA.
B.
a DNA polymerase.
C.
a protein molecule.
D.
an RNA molecule.