Distress Call order: After initiating the call with "MayDay MayDay MayDay"...

1) the name of the station addressed;
2) the identification of the aircraft and aircraft type;
3) the nature of the distress condition;
4) the intention of the person in command;
5) present position, level (i.e. flight level, altitude, etc., as appropriate) and heading;
6) any other useful information.

Looking at the answer options:

'G-BGHG, engine failure, 2500 ft, currently overhead Plymouth, intend landing Plymouth ...' --> INCORRECT. The intention to land is too late in the message order

'G-BGHG, PA28, intend landing Plymouth, currently overhead Plymouth, 2500 ft ...' --> INCORRECT. No mention of the nature of the distress.

'Engine failure, currently overhead Plymouth at 2500 ft, intend landing Plymouth ...' --> INCORRECT. Position is given before the intention of the pilot. No identification of the aircraft (call sign) is given either.

'G-BGHG, PA28, engine failure, intend landing Plymouth, currently overhead Plymouth, 2500 ft ...' --> CORRECT.