Cathode rays cause an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays

A.

are positively charged

B.

are negatively charged

C.

Have mass

D.

travel in straight lines

Correct answer is D

Rays travels in straight lines and finds its way through any opening available. It could be refracted, reflected or transmitted based on any obstacle. Option A,B,C are not the reason why the cathode are coasted shadows