Which of the following are enantiomers?

Which of the following molecules with the molecular formula $C_4H_8O$ exhibits optical isomerism?

When does a given organic compound exhibit optical activity?

The number of optical isomers possible for $3,4-$dichloropentan$-2-$ol is

Solutions of optically active isomers rotate the plane of polarized light in a polarimeter. Match the following columns $(I)$ with $(II), (III)$,and $(IV)$ correctly:

$(I)$ Optical Activity	$(II)$ Form	$(III)$ Sign	$(IV)$ Rotation
$(A)$ Dextrorotatory	$d$	$(+)$	Right
$(B)$ Laevorotatory	$l$	$(-)$	Left
$(C)$ Optically Inactive (Racemic)	$dl$	$(\pm)$	Zero rotation

How many chiral centers (excluding $N$ centers) are there in morphine?