Mark says Simon of Cyrene, who carried Jesus' cross, was the father of whom?

Answer: Alexander and Rufus

Simon of Cyrene, the father of Alexander and Rufus, was coming in from the country when soldiers forced him to carry the cross.

“Now Simon of Cyrene, the father of Alexander and Rufus, was passing by on his way in from the country, and the soldiers forced him to carry the cross of Jesus.”— Mark 15:21 (BSB)