Which one of the following is one of the cross end products formed when a mixture of acetone and acetaldehyde is heated after treating with aqueous sodium hydroxide ?

Question

$\begin {array} {1 1} (1)\;(CH_3)_2C=CH-CHO & \quad (2)\;(CH_3)_2C=CHCOCH_3 \\ (3)\;CH_3-CH=CH-CHO & \quad (4)\;(CH_3)_2CH(OH)\: CH_2\: CO-CH_3 \end {array}$