What happened to the population of mice (both color variations) over time in location A?

Explain the presence of dark-colored mice at location A. Why didn't this phenotype become more common in the population? The dark-colored mice arose in the population at location A by random mutation. The phenotype did not become more common because it did not afford a selective advantage to the mice.

Explanation:

(≧▽≦)

heat a spark and oxygen