Which Airbus military aircraft was developed from the A310 as a multi-role tanker transport?

The Airbus A310 MRTT was developed from the A310 as a multi-role tanker transport.

The A310 MRTT is a military conversion of the A310-300 wide-body airliner. It can carry fuel for aerial refuelling and also perform passenger, cargo, and medical-evacuation missions. Conversions involved structural and systems changes, including the installation of refuelling equipment and military mission systems.

The aircraft served several air forces, including Germany and Canada. It preceded the larger A330 MRTT, which became Airbus’s principal modern tanker-transport platform.

The A310 MRTT is easy to confuse with the A330 MRTT because both combine tanker and transport functions. Their airframes are different: the A310 MRTT is based on the A310, while the later A330 MRTT uses the larger A330 wide-body.