Inspiratory Capacity (IC) is:

Correct option is D

Correct Answer: (d)
Explanation:
Inspiratory Capacity (IC) equals Tidal Volume (TV) + Inspiratory Reserve Volume (IRV) — the maximum volume of air a person can inhale after a normal expiration.
Information Booster:
Typical lung volume relationships:
TV = air per normal breath.
IRV = extra air inhaled after normal inspiration.
ERV = extra air exhaled after normal expiration.
RV = air remaining after maximal exhalation.
Vital Capacity (VC) = TV + IRV + ERV.
Total Lung Capacity (TLC) = TV + IRV + ERV + RV.
IC is useful clinically to assess inspiratory function and reserve.
IC decreases in restrictive lung disease.
Additional Information (Incorrect Options):
(a) TV + ERV equals not IC (it’s part of Vital Capacity rearrangement).
(b) RV + ERV is functional residual capacity (FRC).
(c) TV + IRV + ERV is vital capacity (VC), not IC.