Why are east coast beaches in the u. s. wider and sandier in general than west coast beaches?

Answer:

The East Coast is far from a convergent plate boundary  that is why the east coast beaches in the US are Wider and sandier in general than the west coast beaches.

Explanation:

When the waves approach an irregular shoreline, they speed and break, they hit the points, and slowdown in the beaches that are quiet. Waves behave similarly in east coast causing them to be sandier.

Also, the east coast is far from convergent plate boundary., i.e.: place where 'tectonic plates' move towards each other. So, they have broader walks. East coast has hotels, buildings, casinos as compared to west coast which only have single homes.

answer; (d) anthropology;

fertile good for trade etc