Which of the following is a valid reason for causing degeneracy in a transportation problem ? Here m is no. of rows and n is no. of columns in transportation table.

• A. When the number of allocations is m + n - 1
• B. When two or more occupied cells become unoccupied simultaneously
• C. When the number of allocations is less than m + n - 1
• D. When a loop cannot be drawn without using unoccupied cells, except the starting cell of the loop.