"why do advertisers hire attractive people to endorse their products"

your answer is rising unemployment and inflation.

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.

answer; all over the above; //everybody