Sigma (σ)Factors Can Regulate the Initiation of Transcription

Sigma (σ) factors can regulate the initiation of transcription.Which of the following is not an example of σ regulation?

A) Some σ factors recognize promoters for genes whose products are necessary when the organism is under stress,such as heat shock.
B) Some σ factors recognize promoters for genes whose products are necessary for nitrogen utilization.
C) Bacteriophages may code for specific σ factors that bind the core RNA polymerase and result in recognition of viral promoters.
D) Many σ factors regulate genes associated with embryonic development in eukaryotes.
E) UV irradiation can trigger the use of alternative σ factors.