A Study Indicates That X Months from Now the Population $( 3 + 4 x ) x ^ { - 1 / 2 }$

Multiple Choice

A study indicates that x months from now the population of a certain city will be increasing at the rate of $( 3 + 4 x ) x ^ { - 1 / 2 }$ people per month. By how much will the population increase over the next 9 months?

A) 70 people
B) 80 people
C) 90 people
D) 100 people