Was T.rex a hunter or scavenger?

There is no clear distinction between hunting and scavenging. It is therefore very probably that T.rex was both a hunter and a scavenger. It had a very powerful build., and with its long legs it could easily have chased prey for short distance sprints to overpower them and eat them - it may well have been a lurking predator pouncing on its victims in a short dash, equally it would have scavenged other kills if it was hungry.