https://docs.mulesoft.com/mule-runtime/latest/xa-transactions

A. The time that is allowed to pass without the transaction being ended explicitly After the timeout, the transaction is forcefully rolled-back

It should be A. Basic XA Transaction timeout definition. Transaction rolls back after timeout. The only confusing part is "explicitly". You can image as transaction being ended explicitly when the scope finishes without an exception, at which point transaction commits.

https://docs.mulesoft.com/mule-runtime/3.7/xa-transactions refer this and answer is there - > https://docs.mulesoft.com/mule-runtime/3.7/jboss-transaction-manager-reference

A is correct

https://stackoverflow.com/questions/35941245/bitronix-exceptions-when-sending-jms-to-activemq-muleesb

Mule polls for JMS messages with a polling timeout same as the configured xa transaction timeout (default:60 Secs). So, the polling thread waits a maximum of 60 seconds for a message to arrive in the queue. XA trnsaction begins the moment polling starts. Consider a scenario where the polling thread receives the message very close to the polling timeout ; say at 59th second (XA Transaction is close to timeout here because it began when polling was initiated) . If message processing takes another 5 seconds, total time of the XA Transaction will be 64 seconds (59 +5). Before the processing finishes, transaction manager kills the transaction because it exceeded the XA timeout.

any reference document for this? Mule Docs doesn't have this info.