Answer:
d) founder effect
Step-by-step explanation:
Founder effect is a genetic drift that occurs when a new population is formed by small number of people from a larger population. As a result of this drift, the spread of a disease can increase. For example If a small population moves from a larger population to settle in a desert, the founder effect can occur. If some of the colonizers are carriers of a disease, this disease would spread faster in the small population than if it had been in a larger population.