Why are genes that code for proteins turned on and off at different times?

chemicals, temperature, and light are among the external environmental factors that can determine which genes are turned on and off, thereby influencing the way an Genes are turned on and off in different patterns during development to make a brain cell look and act different from a liver cell or a muscle cell, for example. Gene regulation also allows cells to react quickly to changes in their environments.organism develops and functions.

Explanation:

i believe the answer would be b. hope it : )

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