Mitochondria releases energy for not only neurons, almost any kind of cell
Vitamin D is the vitamin that comes from the sun.
If a repressive protein attaches to the operator RNA polymerase cannot attach to the promoter.
Repressor is a protein which binds to the DNA (or RNA), more precisely to the operator or associated silencers
and thus inhibits the expression of one or more genes. Its mechanism is to block the attachment of RNA polymerase to the promoter. As a result, transcription is stopped.
I believe it is A) Nucleus