Ans. is 'a' i.e., 2nd to fouhThyroid gland is the largest endocrine gland situated in front and sides of lower pa of neck opposite C5-T4 veebrae. The weight of thyroid gland is approximately 25 gm. The gland is made of :-i) Right and left lobesii) Isthmusiii) Pyramidal lobeThe gland lies against veebrae C5 to T1. Each lobe extends from the middle of thyroid cailage to the 4th or 5th tracheal ring. The isthmus lies against the 2nd and 3rd tracheal rings.