Utility patents for inventions are valid for 20 years

Which of the following events will release a noncompensated surety from liability?

A. Release of the principal debtor's obligation by the creditor but with the reservation of the creditor's rights against the surety. B. Modification by the principal debtor and creditor of their contract that materially increases the surety's risk of loss. C. Filing of an involuntary petition in bankruptcy against the principal debtor. D. Insanity of the principal debtor at the time the contract was entered into with the creditor.

In a transportation tableau with m rows and n columns, if there are fewer than n+m-1 allocations, the tableau is said to be ________

Fill in the blank with correct word.