The correct answer is C. The contract is discharged on account of impossibility.
A contract is discharged when one or both parties are no longer able to fulfill their obligations under the contract. This can happen for a number of reasons, including death, bankruptcy, or impossibility.
In this case, A is unable to supply the goods because of a strike at C’s factory. This is an event that was beyond A’s control and that A could not have reasonably foreseen. As a result, the contract is discharged on account of impossibility.
Option A is incorrect because the contract is not void. A void contract is one that is legally unenforceable. In this case, the contract is still valid, but it has been discharged.
Option B is incorrect because the contract is not voidable. A voidable contract is one that can be cancelled by one or both parties. In this case, the contract cannot be cancelled because A is not at fault for the impossibility.
Option D is incorrect because the contract is discharged. A contract is not discharged if one party is unable to fulfill their obligations. In this case, the contract is discharged because A is unable to supply the goods due to an event beyond their control.