What is true about the isolated small tribal populations ?

Options

A. Wrestlers who develop strong body muscles in their lifetime pass this character on to their progeny
B. There is no change in population size as they have a large gene pool
C. There is a decline in population as boys marry girls only from their own tribe
D. Hereditary diseases like color blindness do not spread in the isolated population

Answer

C

Explanation

The marriage between same tribe causes various health related issues in the progeny also.