Of the following, which is the product formed when cyclohexanone undergoes aldol condensation followed by heating ?
Of the following, which is the product formed when cyclohexanone undergoes aldol condensation followed by heating ?

1. [structure: 2-cyclohexylidenecyclohexanone]
2. [structure: bicyclohexyl, OH on carbon adjacent to ring junction, no C=O]
3. [structure: bi-cyclohexylidene with two C=O]
4. [structure: 2-(2-hydroxycyclohexyl)cyclohexanone]