Which brother of Harold Godwinson supported Harald Hardrada's invasion of England?

Tostig Godwinson supported Harald Hardrada’s invasion of England in 1066.

Tostig was Harold Godwinson’s younger brother and had been Earl of Northumbria. A rebellion forced him from that earldom in 1065, and he went into exile after failing to regain power. His hostility toward Harold and the English government led him to seek a foreign ally.

Tostig first launched raids against the English coast in 1066, then joined Harald Hardrada, the Norwegian king who claimed the English throne. Their forces invaded northern England and defeated the earls Edwin of Mercia and Morcar of Northumbria at Fulford near York on 20 September.

King Harold marched north and defeated them at Stamford Bridge on 25 September. Both Tostig and Hardrada were killed. Harold’s exhausting forced march and the battle’s casualties weakened the English army just before William of Normandy landed in Sussex. The other Godwinson brothers listed in the options—Sweyn, Leofwine, and Gyrth—did not lead this Norwegian invasion.