What causes this discrepancy?

A user has configured Mediator M1 to receive and route product information from System X into its
internal applications in chronological order. For each product, M1 receives one “create” event
followed by any number of “update “ events from an AQ Queue via a JMS adapter. M1 can receive
updates to the product at any time of day.
The user claims that incoming messages for each product are received and processed in the
correct chronological order 95 % of the time. However, the messages are being processed out of
order 5 % of the time. This results in critical errors in the target systems. The user expects all
messages pertaining to a product to be unconditionally processed in the order of arrival at M1.
What causes this discrepancy?

A.
The user is running on a four-node SOA cluster and has not configured the inbound JMC
adapter to be a singleton.

B.
The user is running on a single-node SOA environment but has configured the number of
inbound adapter threads to be a value greater than 1.

C.
The given Mediator configuration does not address this sequencing requirement.

D.
The user has configured resequencer worker threads to a value greater than 1 for the Mediator
service engine.

Explanation:
Reference:
http://www.ateam-oracle.com/wp-content/uploads/2014/02/Oracle-Mediator-Resequencer.pdf