In aldol condensation, product of the reaction is -

CONCEPT:

Aldol Condensation Reaction

• Aldol condensation is a reaction where an aldehyde or ketone with at least one α-hydrogen reacts with another aldehyde or ketone to form a β-hydroxy aldehyde or β-hydroxy ketone.
• The reaction involves the formation of a new carbon-carbon bond, followed by dehydration (in some cases) to give an α,β-unsaturated carbonyl compound.

EXPLANATION:

• In a typical aldol condensation:
  • The product is initially a β-hydroxy aldehyde (if an aldehyde is used) or a β-hydroxy ketone (if a ketone is used).
  • This product can further undergo dehydration to form an α,β-unsaturated aldehyde or ketone, but the direct product of aldol condensation is a β-hydroxy aldehyde or β-hydroxy ketone.
• 
• Option 4: β-hydroxy aldehyde is the correct product of the aldol condensation when aldehydes are involved.

The correct answer is β-hydroxy aldehyde.