Nucleophilic aliphatic substitution reaction is mainly of two types: `S_(N)1` and `S_(N)2`. The `S_(N)1` mechanism is a two step process. Reaction velocity of `S_(N)1` reaction depends only on the concentration of the substrate. Since product formation takes place by the formation of carbocation, optically active substrate gives (+) and (-) forms of the product. In most of the cases the product usually consits of `5-20%` inverted product and `80-95%` racemised species. The more stable the carbocation, the greater is the proportion of racemisation. In solvolysis reaction, the more nucleophilic the solvent, the greater is the proportion of inversion.
Which one of the following compound will give `S_(N)1` reaction predominantly?