He climbed 3/4 of a mile in 2/3 of an hour.
Now we're getting somewhere.
Speed = (distance) / (time)
Speed = (3/4 mile) / (2/3 hour)
Speed = (3/4) / (2/3) mile/hour
Speed = (3/4) x (3/2) mile/hour
Speed = 9/8 mile/hour
Speed = 1 and 1/8 mile/hour
That's Choice-C.