A lab observation notes that a public health lesson links roundworm infection with poor sanitation and contaminated soil. The observation points to:

Correct Answer: A

Ascaris eggs survive in contaminated soil

Ascaris eggs can persist in contaminated soil and infect humans when swallowed with unsafe food, water, or dirty hands. Hygiene and sanitation are essential for prevention. This MCQ belongs to the Medical importance topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.