If there is absence of precursor cell of an organ with the subsequent non development of the organ, what is the condition is called as?
(A) Agenesis (B) Aplasia (C) Atresia (D) Atrophy
(A) Aplasia: - Failure of organ to develop with only rudiment of organ present. It occurs, when precursor cells are there but they do not differentiate into the organ.
 Agenesis: - Complete failure of organ to develop, i.e. e complete absence of the organ, with no rudiment. It occurs when there is not precursor cell of an organ.
 Atresia: - Ducts in the body or their openings or any orifice or passage is abnormally closed or absent.
 Atrophy: - Shrinkage in the size of an organ by a decrease in cell size and number.