A body of a certain mass is attached to the end of a 100 cm long string which is swinging back and forth. During each swing, it moves 4 cm from its lowest point to the right, and then it moves 4 cm to the left. One complete swing takes 2 s. If the amplitude of the motion is doubled, so the mass swings 8 cm to one side and then another 8 cm to the other side, the period of this motion will now be:
A. 4 s
B. 8 s
C. 2 s
D. 6 s