An example of people adapting to their environment is

Those who live in high altitudes such as those in the Himalayas have adapted by having a higher red blood cell count to store more oxygen as oxygen levels are low at high altitudes they also have a larger lung capacity to breath in more oxygen per breath. These adaptations are evolutionary and not ones they choose themselves. 

The correct answer should be brand c.

Ithink this answer here is a or d