How did the Black Death travel from Sarai [modern-day Volgograd] to Cairo?

Aging populations can be a problem for developed countries because a) there are fewer younger workers coming into the workforce. b) most older workers demand top-level pay and full benefits. c) many older people are skilled in manufacturing, not technology. d) younger workers cannot find jobs when older people work longer.

Which of the following phrases best describes american society in the early 1900s

What emperor was given credit for having the aqueducts built