An Airline Offers Daily Flights Between Chicago and Denver $C = \sqrt { 0.2 x + 1 }$

Multiple Choice

An airline offers daily flights between Chicago and Denver. The total monthly cost C (in millions of dollars) of these flights is modeled by $C = \sqrt { 0.2 x + 1 }$ , $x \geq 0$ , where x is measured in thousands of passengers. The total cost of the flights in June is 2.8 million dollars. How many thousand passengers flew in June? Round your answer to the nearest thousand.

A) 19 thousands passengers
B) 44 thousands passengers
C) 34 thousands passengers
D) 39 thousands passengers
E) $9$ thousands passengers