What were the changes in the volleyball rules over time?

I. In 1920, the rule was established that each team could only hit the ball three times, with any part of the body above the waist.
II. In 1922, the number of touches per team was limited to three, with any part of the body from the waist up.
III. In 1924, the need for a 2-point advantage to win each set was established.
IV. In 1964, the blockers were allowed a second hit.
a. I and II are correct.
b. II and III are correct.
c. III and IV are correct.
d. I, II, III, and IV are correct.