What do you understand by Tyndall effect ? Which of the following will show it ?

(a) salt solution

(b) milk

(c) copper sulphate solution

(d) starch solution

Colloids scatter a beam of light passing through them. This phenomenon is known as the Tyndall effect.

Milk and starch solution will show Tyndall effect.

Explanation:
Milk and starch solution are colloids. Both have large particles to scatter light. Thus, they show Tyndall effect.
Salt and copper sulphate solutions are true solutions. They have small particles and do not scatter light. Thus, they do not show Tyndall effect.