Compound P on treatment with $$\mathrm{CH_2N_2}$$ produces compound Q. Compound Q on reaction with HI produces two alkyl iodides R and S. Alkyl iodide S with the higher number of carbon atoms on reaction with KCN followed by hydrolysis gives 3-methylbutanoic acid. Compound P is

A

2-butanol

B

1-butanol

C

2-methyl-2-propanol

D

2-methyl-1-propanol