Physiology General d9eabe5e Half life of T4 is A 20 minutes B 12 hours C 1 day D 6 days High-Yield Explanation Ans: D. 6 days(Ref: Ganong 25th/e p. 338-341; Understandings of medical physiology p. 7l9)Half life of T3 = 1 dayHalf life of T4 = 6 days.