A species of snail lives in the intertidal zone along the coast of New England. The dark-colored variety of the species is more common in northern New England, the light-colored variety is more common two hundred miles away in southern New England, and both varieties are commonly found together in central New England. What is the best explain the observed distribution pattern of the snails?

The correct answer is: Climatic Adaptation.

Explanation:

The coastal region of the northern part of New England is much colder than the southern part.Snails inhabiting the northern England coasts possess dark coat colour. This help the snails to absorb more solar energy and keep their body warm  in the cold environment as dark colours absorb more solar energy and reflects less solar energy.Snails inhabiting the southern England coasts possess light coat colour. This help the snails to radiate more solar energy and keep their body cool in the comparatively warmer environment that prevails here. Light colours reflect more solar energy  and absorb less solar energy.In Central England, the temperature is moderate. Hence, snails belonging to both dark coat and light coat varieties are found here.