Which of the Following Is Not True for a Random $$a \leq x \leq b$$

Multiple Choice

Which of the following is not true for a random variable X that is uniformly distributed over the interval $$a \leq x \leq b$$ ?

A) E ( X ) = ( a + b ) / 2
B) = $V(X) =(b-a) ^{2} / 12$
C) $\sigma = ( b - a ) / 6$
D) f ( x ) = $\frac { 1 } { b - a } \text { if } a \leq x \leq b$