What team did Bobby Orr play for in his 5th season?

Context: Robert Gordon Orr OC is a Canadian former professional ice hockey player, widely acknowledged as one of the greatest of all time. Orr used his ice skating speed, scoring, and play-making abilities to revolutionize the position of defenceman. He played in the National Hockey League for 12 seasons, the first 10 with the Boston Bruins, followed by two with the Chicago Black Hawks. Orr remains the only defenceman to have won the league scoring title with two Art Ross Trophies. He holds the record for most points and assists in a single season by a defenceman. Orr won a record eight consecutive Norris Trophies as the NHL's best defenceman and three consecutive Hart Trophies as the league's most valuable player. Orr was inducted into the Hockey Hall of Fame in 1979 at age 31, the youngest to be inducted at that time. In 2017, Orr was named by the National Hockey League as one of the "100 Greatest NHL Players" in history.

Answer: Bobby Orr played for the Boston Bruins in his 5th season in the National Hockey League (NHL).

He played in the NHL for 12 seasons, the first 10 with the Boston Bruins, followed by two with the Chicago Black Hawks.