Which of the following compounds gives only a primary alcohol on reaction with a Grignard reagent $(RMgX)$?

Which of the following compounds undergoes aldol condensation?

The major product of the following reaction is:

An organic compound with the molecular formula $C_9H_{10}O$ forms a $2,4-DNP$ derivative,reduces Tollen's reagent and undergoes Cannizzaro reaction; on vigorous oxidation it gives $1,2-$benzenedicarboxylic acid. The structure of the organic compound is:

The above reduction can be best carried out by

The reaction of $5-$methylenecyclohex$-2-$enone with $2$ equivalents of $HBr$ yields which of the following products?