A physical feature, such as a body of water, might actually aid transportation and migration because ocean travel may be easier than overland travel. However, if that physical feature hinders migration it is an example of

an intervening obstacle

Explanation:

A physical feature that hinders or obstructs the migration of any species form one place to another, it acts as an intervening obstacle for migration.

It is mostly considered that the water bodies served as the best option or body for migration of species form one place to another. It is a seasonal migration for climatic conditions and in search of food. Migration over the oceans is much easier that travel over the land masses.

Many bird species as well as animals migrate to far off places in search of food.

But sometimes, the physical feature provides difficulty or obstructs the migration. It is an example of the intervening obstacle of the physical feature.

the answer is b antarctica