Excuse me... The question isn't clear I think there are some options or something, it would be helpful for us to answer if you add those too.
Answer:
The gene for the protein is turned on and off at different times.
Explanation:
The turning on and off of the gene is described as gene regulation. This process is important because it enables the cells to react quickly to the changes in the environment.
Note that , this process mostly occur at transcription level during gene expression , and help in determining the amount of protein made by a gene.
I think it's A.
phenotype frequency is the number of individuals in a population that have a specific observable trait or phenotype
The sun
The sun produces our hear
