Which of the following are correct statements regarding unimolecular SN1

Question

$\begin{array}{1 1} \text{a)AgNO3 increases solvolysis it is called electrophilic catalysis.} \\ \text{ b)The more acidic the nucleophilic solvent the faster is the rate of solvolysis.} \\ \text{ c)The more stable $R^+$ the less inversion and more raceimisation occurs}\\ \text{ d)All the above} \end{array}$