A.\(\left( {\int {f\left( x \right)dx} } \right)' =  - f'\left( x \right)\)
B.\(\left( {\int {f\left( x \right)dx} } \right)' = f'\left( x \right)\)
C.\(\left( {\int {f\left( x \right)dx} } \right)' =  - f\left( x \right)\) 
D.\(\left( {\int {f\left( x \right)dx} } \right)' = f\left( x \right)\)