Answer : 3. "Roundworm"
Explanation :

The common name of Ascaris is:

(C) Roundworm

Ascaris is a genus of parasitic roundworms, and the common name "roundworm" is often used to refer to these worms. Ascaris lumbricoides is a species of roundworm that commonly infects the intestines of humans. So, the correct answer is (C) Roundworm.