What major event occurred during the first year of herbert hoover's presidency?
a. the bombing of pearl harbor
b. the explosion of the hindenburg
c. the sinking of the lusitania
d. the stock market crash

During Pearl Harbor Franklin D. Roosevelt was President
During The Explosion of the Hindenburg, the current president was also Franklin D. Roosevelt
During the Sinking of the Lusitania, Woodrow Wilson was President
During the stock market crash, Herbert Hoover was President

So It would be D. The Stock Market Crash

The constant presence of diseases or infectious agents within a given geographic area or population group. it may also refer to the usual prevalence of a given disease with such area or group. it includes holoendemic and hyperendemic diseases. a holoendemic disease is one for which a high prevalent level of infection begins early in life and affects most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than do children (malaria in many communities is a holoendemic disease). a hyperendemic disease is one that is constantly present at a high incidence and/or prevalence rate and affects all groups equally. so probably family history.