Question

Assertion (A): Ascaris lumbricoides completes its entire life cycle within the small intestine. Reason (R): Larvae of Ascaris undergo extra intestinal migration.

• A. Both (A) and (R) are true. (R) is the correct explanation for (A)
• B. Both (A) and (R) are true. (R) is not the correct explanation for (A)
• C. (A) is true. But (R) is false
• D. (A) is false. But (R) is true

Hint:

*Ascaris* larvae take the scenic route (liver $\rightarrow$ heart $\rightarrow$ lungs) before becoming adults in the intestine.

Answer 1

The Correct Option is D

Step 1: Read the two lines.
The Assertion says Ascaris finishes its whole life cycle inside the small intestine. The Reason says its larvae travel outside the intestine. We must test each.

Step 2: Recall the Ascaris life cycle.
Ascaris is the common roundworm of humans. After eggs hatch, the young larvae do not stay put. They bore into the gut wall and enter the blood.

Step 3: Follow the larval journey.
The larvae are carried to the liver, then the heart, and then the lungs. From the lungs they climb up the windpipe and are swallowed again to reach the intestine.

Step 4: Judge the Assertion.
Because of this long trip through liver and lungs, the worm does not complete its whole cycle inside the small intestine. So the Assertion is false.

Step 5: Judge the Reason.
The Reason says the larvae undergo migration outside the intestine. That is exactly what happens. So the Reason is true.

Step 6: Pick the option.
The Assertion is false and the Reason is true, which is the fourth option.
\[ \boxed{\text{(A) is false. But (R) is true}} \]