Which one of the following statements concerning E2 reactions of alkyl halides is true?(a)...

Which one of the following statements concerning E2 reactions of alkyl halides is true?

(a)     The rate of an E2 reaction depends only on the concentration of the alkyl halide.

(b)     The rate of an E2 reaction depends only on the concentration of the base.

(c)     The bond and the (X = halogen) bond are broken in the same step.

(d) Alkyl chlorides generally react faster than alkyl bromides.