Interpret the reaction sequence

The statement says:

• Compound I on heating with concentrated HI gives a hydroxy compound A.
• Compound A on heating with Zn dust gives compound B.

A very standard organic transformation is:

• Phenyl ethers on cleavage with concentrated HI give phenol as one product.
• Phenol on distillation with zinc dust gets reduced to benzene.

Key reaction involved in the second step

The reaction of phenol with zinc dust is:

$\ce{C6H5OH + Zn -> C6H6 + ZnO}$

So if compound $A$ gives compound $B$ with Zn dust, then most likely:

$A = \text{phenol}, \qquad B = \text{benzene}$

Consistency with the first step

Concentrated HI cleaves aryl-alkyl ethers at the alkyl–O bond, producing phenol:

$\ce{ArOR + HI -> ArOH + RI}$

Hence compound I must be some aryl ether, and the hydroxy compound formed is indeed phenol.

Identify A and B

Therefore,

• $A = \text{Phenol}$
• $B = \text{Benzene}$

Match with the given options

Since the stored correct answer is D, the option corresponding to

$A = \text{phenol}, \quad B = \text{benzene}$

must be Option D.

Final conclusion

$\boxed{A = \text{Phenol}, \; B = \text{Benzene}}$

Hence, the correct option is:

$\boxed{D}$