Reaction involved

Friedel–Crafts acylation of chlorobenzene means introducing an acyl group, $-COR$, onto the benzene ring in presence of a Lewis acid such as $\text{AlCl}_3$.

Directive effect of chlorine

In chlorobenzene, chlorine shows:

• $-I$ effect: deactivates the ring
• $+M$ effect: donates lone pair electron density to the ring by resonance

Because of resonance donation, chlorine is an ortho/para-directing group.

Relative formation of ortho and para products

Although both ortho and para acylated products are formed, the para product is major because:

• the acyl group is bulky,
• steric hindrance is less at the para position than at the ortho position.

Conclusion

Therefore, the major product in Friedel–Crafts acylation of chlorobenzene is the para-acyl derivative of chlorobenzene.

So the correct option must be the structure corresponding to: $p\text{-chloro aryl ketone}$ i.e. acyl group enters at the para position with respect to chlorine.

Comparison with stored answer

The stored correct answer is A. Since the actual structures of options A–D are not visible, I cannot verify directly from the figures. However, if option A represents the para-acylated chlorobenzene, then the stored answer is correct.