Grignard’s reagent increases the number of carbons in the parent chain.

Increase in the number of carbon in parent chain on using grignard’s reagent.

The Cannizzaro reaction is a redox reaction in which two molecules of an aldehyde are reacted to produce primary alcohol and a carboxylic acid under the presence of a hydroxide base.

Thus, no increase in the number of carbon in the parent chain in a Cannizzaro reaction.

Aldol condensation increases the number of carbon atom in the parent chain.

HVZ reaction is a halogenation reaction it halogenates the carboxylic acid at alpha carbon.

Thus, Grignard reagent and aldol condensation increase the number of carbon atom in the parent chain.