Difference between natural and artificial factors of population change​

Why are people more likely to marry individuals with social and cultural backgrounds very similar to their own? a. parents and other family members always exert pressure to marry within the group. b. people spend a great deal of time alone, and therefore can have few opportunities for meeting people. c. people develop irrational fears of out-group members and are scared to date them. d. people have greater access to individuals like themselves.

Aresearcher conducts a focus group to learn about attitudes towards hygiene and disease prevention. two weeks after the focus group, the researcher learns one of the subjects had a heart attack at home and was hospitalized, but made a full recovery. based on dhs regulations, the researcher report this event to the irb? no, this does not need to be reported since the subject had the heart attack when they were home, not at the focus group.no, this does not need to be reported since it is unrelated to participation in the study.no, this does not need to be reported because two weeks have passed.no, this does not need to be reported since the subject recovered.

Is it true the ancient egyptians created a calendar that had 10 days in a week