Grignard product is that product which forms because of nucleophilic addition reaction.

Aldehydes on reaction with Grignard reagent gives Grignard product.



In Grignard reagent R^$$-$$ is a very strong base, so it will react with acidic H⁺ of $$-$$COOH group first. As Grignard reagent is one equivalent, so no reagent will remain to react with aldehyde group.



Here also in alcohol functional group ($$-$$CH₂OH)  H⁺ is acidic so here acid base reaction will occur.

In option (A) only one functional group ($$-$$ CHO) present so it will give Grignard product by nucleofilic addition reaction.

In option (C) functional group ether ($$-$$ CH₃) does not react with RMgX so aldehyde functional group will react with RMgX and give Grignard product.