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. There should be no alpha hydrogen (hydrogen attached to alpha carbon) as there will be no enolization and aldol condensation.

Option (iv) will not give Cannizaro reaction as it contains alpha hydrogen.

Option (i), (ii) and (iii) will give Cannizzaro reaction as they do not have alpha hydrogen.

Step 1 Mechanism;

Step 2 Mechanism;

Step 3 Mechanism;

Benzaldehyde Cannizaro reaction