At Today's Rate of Consumption, the World's Known Reserves of Tantalum

At today's rate of consumption, the world's known reserves of tantalum will last about ________________ more years at today's rate of consumption, but if everyone in the world began consuming tantalum at the rate of U.S. citizens, then it would last for only ________________ years.

A) 15; 5
B) 200; 50
C) 50; 5
D) 200; 15
E) 50; 15