Identify A and B in the following sequence of reaction:

In side-chain chlorination of toluene using $$Cl_2/h\nu$$, chlorine substitutes the benzylic hydrogen atoms to form $$Ph-CH_2Cl$$, $$Ph-CHCl_2$$, or $$Ph-CCl_3$$ depending on the extent of chlorination. Subsequent hydrolysis replaces chlorine atoms with hydroxyl groups.

Option A is incorrect because $$Ph-COCl$$ cannot be formed in the first step. The reagents $$Cl_2/h\nu$$ only cause free-radical chlorination and do not introduce an oxygen atom or generate a carbonyl group.

Option C is incorrect because hydrolysis of $$Ph-CH_2Cl$$ produces $$Ph-CH_2OH$$ (benzyl alcohol). Formation of $$Ph-CHO$$ (benzaldehyde) is not possible from an intermediate containing only one chlorine atom.

Option D is incorrect because hydrolysis of $$Ph-CHCl_2$$ first forms the unstable gem-diol $$Ph-CH(OH)_2$$, which loses water to give $$Ph-CHO$$ (benzaldehyde). Formation of $$Ph-COOH$$ (benzoic acid) requires the intermediate $$Ph-CCl_3$$, not $$Ph-CHCl_2$$.

Option B is correct because $$Ph-CHCl_2$$ (benzal chloride) on hydrolysis forms the unstable gem-diol $$Ph-CH(OH)_2$$, which dehydrates to yield $$Ph-CHO$$ (benzaldehyde).

Therefore, the correct sequence is:

$$Ph-CHCl_2 \rightarrow Ph-CHO$$

Hence, Option B is the correct answer.