Correct Answer: B
Explanation:
A number of crystals, liquids, solutions and vapors rotate the electric vector of linearly polarized light passing through them, this property being known as optical activity. The rotation is proportional to the thickness of the medium traversed and its sense is related to the direction of the light beam. Rotations that are clockwise to an observer looking against the direction of the light beam are said to be right handed or dextrorotatory and are considered positive; anticlockwise rotations are said to be left handed or laevorotatory.