In traditional units of weight used in Unani and ancient Indian systems, the descending order is based on the size of the unit from largest to smallest.
Chhatank is larger than Tola, which is larger than Dirham.
Dirham is larger than Daam, and Daam is larger than Dang.
So the correct descending order is: Chhatank (D), Tola (E), Dirham (B), Daam (C), and Dang (A).
Therefore, the answer is DBECA.