CBSE 2025 · Region 5 · Set 2 · Q16 · 1 mark
Assertion (A): Lymphocytes arise from bone marrow and present in the blood and lymph and serve as natural killer cells. Reason $\displaystyle (R)$ : Lymphocytes migrate to thymus, where they develop into T-cells and begin to mature.
Official answer
From CBSE’s own marking scheme for this paper.
(A)
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Human Health and DiseaseImmunityUnderstandassertion_reasonmedium
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CBSE Class 12 Biology past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.