Which of the following shows every interval on which f (x )is decreasingf(x) is decreasing? Choose the correct answer below. A. (a comma b )comma (c comma d )comma (f comma g )(a, b), (c, d), (f, g) B. (a comma b )comma (c comma e )(a, b), (c, e) C. (b comma d )comma (f comma g )(b, d), (f, g) D. (a comma b )comma (c comma e )comma (f comma g )