How Does Tryptophan, the End Product of the Trp Operon

Multiple Choice

How does tryptophan, the end product of the trp operon, function in the regulation of the operon?

A) Trp binds to and inhibits the repressor, thus allowing transcription of the operon.
B) Trp binds to and activates the repressor, which then binds to DNA to allow transcription of the operon.
C) Trp binds directly to DNA and inhibits transcription of the operon.
D) Trp binds to and changes the conformation of the repressor, which can then bind DNA and block transcription of the operon.