A 50:50 mixture of the (R) and (S) enantiomers of a chiral compound shows no net optical rotation. The reason is that

1. Athe rotations caused by the two enantiomers are equal in magnitude and opposite in sign, so they cancel (external compensation)
2. Beach molecule of the mixture has an internal plane of symmetry
3. Cthe molecules of the mixture are achiral
4. Dthe (R) form is rapidly converted into the (S) form only in the polarimeter tube