Answer:
(d) soap.
Step-by-step explanation:
A soap is obtained by alkaline hydrolysis of a fat to yield the soap and glycerol. This process is known as saponification.
A soap solution is usually basic. Since phenolphthalein turns pink in an alkaline solution, then when phenolphthalein is added to a soap solution, the solution soon turns pink because it is alkaline in nature.
As a matter of fact, a soap sometimes has almost the pH of baking soda!