At the End of a Long Day What Is the Relative

At the end of a long day what is the relative level of CO and how does this in turn affect the expression of the FT gene and thus flowering?

A) CO levels are high. CO binds to the FT promoter, initiating transcription and thus inhibiting flowering.
B) CO levels are high. CO binds to and inhibits FT expression, resulting in the inhibition of flowering.
C) CO levels are high. CO binds to and inhibits FT expression, resulting in the promotion of flowering.
D) CO levels are high. CO binds to the FT promoter, initiating transcription and thus promoting flowering.
E) CO levels are low. CO is displaced from its inhibiting position on the FT promoter, resulting in the promotion of flowering.