What happens when pieces of rock bounce along the bed of a river

Icant awnser the qustion bc u have the planets not listed

Ithink this answer here is a or d

Many foreign companies buy/build hotels in areas therefore most of the profit from tourism goes to these companies rather than the local economy or local people. 
also, these foreign companies might only employ foreign workers with experience meaning they receive more pay whereas local people would be employed for low skilled jobs and lower pay. 

thats all i can think hope it : )