Which of the Following Statements Is (Are)true of S_N1 Reactions

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

A) The rate of an S_N1 reaction depends on the concentration of the alkyl halide.
B) The rate of an S_N1 reaction depends on the concentration of the nucleophile.
C) S_N1 reactions of alkyl halides are favored by polar solvents.
D) The rate of an S_N1 reaction depends on the concentration of the alkyl halide and S_N1 reactions of alkyl halides are favored by polar solvents.
E) The rate of an S_N1 reaction depends on the concentration of the alkyl halide and the concentration of the nucleophile,and S_N1 reactions of alkyl halides are favored by polar solvents.