Which is the most effective way to meet the business requirement?

ABC Travel offers a night reservation service, exposed as a web service. XYZ Stays offers a hotel
reservation service, also exposed as a web service. ABC and XYZ will not change their web
service. A startup company has contacted you for advice about designing a new service that
combines flight and hotel reservations, which they will offer as a web service.
The startup company plans to provide their service by implementing a portable Java EE solution
that aggregates the two services offered by ABC Travel and XYZ Stays, a combined reservation
succeeded.
Only if both the flight reservation and the hotel reservation succeed
Which is the most effective way to meet the business requirement?

A.
The startup company should implement their new service as a web service that uses an XA
transaction manager.

B.
The startup company cannot implement their new service as a web service, but must use an
enterprise JavaBean (EJB) component to gain transaction propagation.

C.
The startup company should implement their new service as a web service by calling the two
existing services, and implementing their own compensating transaction.

D.
The startup company can implement their new service as a web service by calling the two
existing services in a single transaction, relying on transaction propagation to support this
business rule.