Answer:C. A mistake of value support the cancellation of a contract.
Explanation:
The law of equity says ' he who comes to equity must come with a clean hand. Although the law requires the enforcement of a valid contract but the precensce of a substantial mathematics mistakes make the contract unenforceable.
It's not a bilateral mistake because it's from one the parties, though not all unilateral mistakes can cancel a contract especially when done with negligence.
The contract been below the price of contract of similar nature is not a valid excuse for non performance after agreement.