Why do people who live on islands tend to develop very different customs from those who live in other parts of the world?
a.
they tend to be more isolated from outside cultures.
b.
their culture is based on entertaining tourists.
c.
island populations tend to be dense.
d.
the severity of tropical storms keeps visitors away.

A.  They tend to be more isolated from outside cultures.

Explanation:

As most often island nation of the world are cut off from the rest of the worlds they thus experiences a sense of belong to the islands and they relate themselves to the lands of the island as they are mostly indigenous people and they remain separate from the outer worlds and as the islands have a low density of population they generally avoid much contact with the outer world people. They practice their own ancient ancestors customs and thus show a primitive type of living which is traditional and environmental made.