Preorder - BCEIFDGHJK means root node is B. Inorder - EICFBGDJHK
So search for B in Inorder traversal. Everything to the left of B is left subtree and to the right of B is right subtree in inorder traversal. So we understand that EICF forms the left subtree and GDJHK forms the right subtree of B.
Repeating, this for EICF, we find that C is the root and EI (or IE) forms the left subtree and F forms the right subtree of C. Similarly, for GDJHK, D is the root. G is the left subtree and JHK (or JKH) forms the right subtree.
Therefore, we have the tree as drawn below:
Now finding postorder is very easy. The answer is option (A) IEFCGJKHDB