Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small.The larvae then pass through the stomach for a second time into the intestine, where they become adult worms

Ascaris is endoparasite of man. It inhabits the small intestine more frequently of children than of adults...Thus, option A is right ans..

Ascaris lumbricoides is an endoparasite of man and inhabits the small intestine.

Explanation:
Ascaris lumbricoides is a species of roundworm or nematode that infects humans. It is one of the most common parasites found in humans worldwide. This parasitic worm has a cylindrical, elongated body that can grow up to 35 cm in length. It is typically found in areas with poor sanitation and hygiene practices.

Life cycle of Ascaris lumbricoides:
1. Ingestion: The life cycle of Ascaris lumbricoides starts when a person ingests the infective eggs, which are present in contaminated food, water, or soil.
2. Larval stage: Once the eggs are ingested, they hatch in the small intestine and release larvae.
3. Migration: The larvae penetrate the intestinal wall and enter the bloodstream, where they are carried to the liver and lungs.
4. Pulmonary stage: In the lungs, the larvae migrate through the alveoli and bronchioles, causing respiratory symptoms such as coughing and wheezing.
5. Re-ingestion: The larvae are then coughed up and swallowed, returning to the small intestine.
6. Adult stage: In the small intestine, the larvae mature into adult worms and attach themselves to the intestinal wall.
7. Reproduction: The adult female worms produce thousands of eggs, which are passed in the feces of the infected individual, completing the life cycle.

Location in the human body:
Ascaris lumbricoides primarily inhabits the small intestine of humans. The adult worms attach themselves to the intestinal wall and feed on the contents of the small intestine, causing symptoms such as abdominal pain, diarrhea, and malnutrition. They can also obstruct the intestinal lumen, leading to bowel obstruction in severe cases.

It is important to note that Ascaris lumbricoides is not found in the duodenum, rectum, or colon. Its life cycle involves migration from the intestines to the liver and lungs, but the adult worms reside in the small intestine.