Match List I with List IIList IList IIA. Physical barrierI. Interfero…

The correct answer is Option (4) → A-IV, B-II, C-III, D-I

(A) Physical barrier — this matches (IV) Skin. The skin is the main barrier that physically stops microbes from entering the body. Mucus coating the respiratory, gastro-intestinal and urogenital tracts also traps microbes.

(B) Cellular barrier — this matches (II) Natural Killer cells. Certain white blood cells, such as polymorpho-nuclear leukocytes (PMNL-neutrophils), monocytes and natural killer cells, as well as macrophages, can destroy microbes.

(C) Physiological barrier — this matches (III) Tears from eyes. Acid in the stomach, saliva in the mouth and tears from the eyes all prevent microbial growth by their chemical action.

(D) Cytokine barrier — this matches (I) Interferons. Virus-infected cells secrete interferons, proteins that protect the uninfected cells from further viral infection.

Note: A similar question was also asked in CUET (UG) 2026 on 19-05-2026 (Slot 1).

NCERT Extract:
Innate Immunity – “… Innate immunity consist of four types of barriers. These are —
(i) Physical barriers : Skin on our body is the main barrier which prevents entry of the micro-organisms. Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body.
(ii) Physiological barriers : Acid in the stomach, saliva in the mouth, tears from eyes–all prevent microbial growth.
(iii) Cellular barriers : Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes.
(iv) Cytokine barriers : Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.”