Meso-tartaric acid is optically inactive due to the presence of

Which of the following compounds is an optically active compound?

Which of the following compounds exhibits optical isomerism?

$A$ racemic mixture is formed by mixing two

Which of the following compounds does not exhibit optical isomerism?

Optically active $(S)-2-$methoxypropanal on reaction with $MeMgX$ gives a mixture of alcohols. The major diastereomer $P$ on treatment with $MeI / K_2CO_3$ gives an optically inactive compound. $P$ is