System crash – A hardware, software, or network error may cause a computer to fail or hang during an ongoing transaction.
exception – A transaction may be failed if necessary data not found, or an exception condition met. For example, customer A tries to purchase an item online. Assume that only two such items are available when A starts his transaction and both of them purchased by other customers. When A reaches end of the transaction, the items are not available hence the transaction is cancelled or failed.
so i think deadlock is ans