Ans should be D)none of these as Choice A , B,C are giving only 90 demand and supply allocations whereas given demand and supply are 100.
Method is as per vogel algo summary
1)first calculate penalty(difference between two min values ) for each row and column 2)
now select the column with max penalty and search the least cost in that col/row
4)assign the max allocations and update the row/column demand supply
5)cross out the exhausted row/colum
Repeat the above procedure
Correct ans should be X11=20 , X, Total cost = 180