# How many optical isomers are possible for the compound abdc - cabd?

(a) Two (b) Four (c) Three (d) One

The compound contains 2 chiral carbon atoms and it has a plane of symmetry.
Hence the number of optical isomers = $2^{n-1}+2^{n/2-1}$
$\qquad=2^{2-1}+2^{2/2-1}$
No. of . optical isomers =3
Hence c is the correct answer.