Glaciers can only form when;
a. there is an ice age.
b. there is a u-shaped valley in the mountains.
c. the amount of snow exceeds the amount of rain.
d. more snow falls than melts.

Option (d) is the correct answer.

Explanation:

Glaciers are defined as the large body of ice which tend to flow slowly in the downward direction on a slope.

Glaciers are formed because snow falls and remains in the same area for years and then it results in the formation of ice.

This ice then due to melting or large mass slopes downward and reaches into the ocean(s).

Thus, we can conclude that Glaciers can only form when more snow falls than melts.