Two friends are sitting on a seesaw at the park. The height, , of the left seat, in inches above the ground, is modeled by a sine function. Let t represent the time, in seconds, since the friends started seesawing. 0 1 2 3 4 5 6 24 48 24 0 24 48 24 If the friends start seesawing with the plank in a level position, how long does it take for the friend in the left seat to move upward, downward, and then back to the initial position? A. 4 seconds B. 2 seconds C. 3 seconds D. 6 seconds