Width of central maximum ${\beta }_{cm}=\frac{2\lambda D}{a}$, where $a$ is the slit width and $D$ is the slit-screen distance.

(A) $\beta \propto \lambda$, so increasing $\lambda$ increases width - Correct.

(B) Opposite of (A) - Incorrect.

(C) $\beta \propto \frac{1}{a}$, so decreasing slit width increases width - Correct.

(D) Opposite of (C) - Incorrect.

(E) For shorter wavelengths the energy delivered per unit area at the central maximum is higher - typically taken as correct in this context.

In this question options: A, C and E are correct, which does not match to any options given in the exam. Hence, this question is a bonus question.