If $\int _ { 2 } ^ { 1 } 5 f ( x ) d x = 5,$

Multiple Choice

If $\int _ { 2 } ^ { 1 } 5 f ( x ) d x = 5,$ then $\int _ { 1 } ^ { 2 } 2 f ( x ) d x$ is

A) -5
B) -2
C) 2
D) 5
E) Impossible to determine