When researchers untangled the genetic code and the structure of genes in the 1950's and 1960's, they began to see genes as
a collection of plans, one plan for each protein. They also discovered that A) genes are not self-regulating. B) genes cannot regulate protein production. C) genes do not produce proteins all the times. D) genes were working to build proteins at a constant rate

Gene activity is highly regulated both before and after transcription. This happens through the activity of transcription factors, which initiate gene expression. Regulation of their activity helps to control the activity of the genes that they in turn regulate

This is important for the cell's identity and being able to respond to signals and environmental cues. Genes can be self-regulating and can regulate protein production (so A and B are false). They also don't work to build proteins at a constant rate, they build proteins according to the needs of the cell. E.g. the protein needs of a muscle cell are very different from the needs of a brain cell, so D is false.

Therefore, genes do not produce proteins all the time.