The sigma (σ) subunit of prokaryotic RNA polymerase: (A) Binds the antibiotic rifampicin, (B) Is inhibited by α-amanitin, (C) Specifically recognizes the promoter site, (D) Is part of the core enzyme
Answer is C. Sigma (σ) factor recognizes promotor sequences on the DNA template. Different factors recognize a different group of genes.
α-amanitin inhibit RNA polymerase II of eukaryotes.
Rifampicin inhibits β-subunit of RNA polymerase.
Sigma unit is not a part of core enzyme; it is a part of holoenzyme.

RNA polymerase (holoenzyme) = core enzyme (2α, β,( β’) + sigma (σ) subunit