Fruits stored in a cold chamber exhibit longer storage life because

Answer

rate of respiration is decreased

(a) Exposure to sunlight is prevented: This is not the main reason for longer storage in a cold chamber. Shelf life increases primarily due to low temperature, not merely absence of sunlight. Verdict: Incorrect.
(b) Concentration of carbon dioxide in the environment is increased: Higher CO2 can help in controlled-atmosphere storage, but a cold chamber by itself works mainly through low temperature. Verdict: Incorrect.
(c) Rate of respiration is decreased: Low temperature slows metabolic and respiratory activity in fruits, delaying ripening and spoilage. Verdict: Correct.
(d) There is an increase in humidity: Humidity may reduce water loss, but it is not the principal reason for longer storage life in a cold chamber. Verdict: Incorrect.