differentiable over the interval ( −1 , 9 ) ? a. yes, but it would not be if the interval were ( −1 , 1 ) . b. no, but it would be if the interval were ( −1 , 1 ) . c. yes, and it would be if the interval were ( −1 , 1 ) . d. no, and it would not be if the interval were ( −1 , 1 ) .