The Following Items Are Positioned in Sequence: a Source of a Beam

Multiple Choice

The following items are positioned in sequence: A source of a beam of natural light of intensity $I _ { 0 }$ , three ideal polarizers A, B, and C; and an observer. Polarizer axis angles are measured clockwise from the vertical, as viewed by the observer. The axis angle of polarizer $A$ is set at $0 ^ { \circ }$ (vertical) , and the axis angle of polarizer $C$ is set at $50 ^ { \circ }$ . The axis angle of polarizer $B$ is set at $120 ^ { \circ }$ . What is ratio of the intensity of the beam at the observer to the intensity $I _ { 0 }$ of the source?

A) $0.015$
B) $0.035$
C) $0.020$
D) $0.025$
E) $0.030$