Give the mechanistic symbols (SN1, SN2) that are most consistent with each of the following statements: (a) Methyl halides react with sodium ethoxide in ethanol only by this mechanism. (b) Unhindered primary halides react with sodium ethoxide in ethanol mainly by this mechanism. (c) The substitution product obtained by solvolysis of tert-butyl bromide in ethanol arises by this mechanism. (d) Reactions proceeding by this mechanism are stereospecific. (e) Reactions proceeding by this mechanism involve carbocation intermediates. (f) This mechanism is most likely to have been involved when the products are found to have a different carbon skeleton from the substrate. (g) Alkyl iodides react