Put the Following Events of Transcription in Chronological Order

Multiple Choice

Put the following events of transcription in chronological order.
1) Sigma binds to the promoter region.
2) The double helix of DNA is unwound,breaking hydrogen bonds between complementary strands.
3) Sigma binds to RNA polymerase.
4) Sigma is released.
5) Transcription begins.

A) 2,3,4,5
B) 2,3,1,4,5
C) 3,1,2,5,4
D) 3,2,1,4,5