What is genetic drift in the context of population genetics?

Which of the following statements about genetic drift are true?

I) Genetic drift is most pronounced in large populations.

II) Genetic drift can reduce genetic variation.

III) Genetic drift is due to chance events, not differences in fitness.

True or False: if false, choose the answer that best corrects the statement.

The founder effect and population bottlenecks will generally decrease genetic variation in a population even if the population eventually returns to a large population size.

Humans first evolved in sub-Saharan Africa. Populations of modern humans likely migrated from Africa, populating the rest of the world within the last 100,000 years. A general trend observed in the human population is that the farther a native population is from Africa, the less genetic diversity in that population. What could explain this trend?