One End of a Horizontal String of 0

Multiple Choice

One end of a horizontal string of 0.40 mg/m mass per unit length is attached to a small-amplitude mechanical 60 Hz vibrator. The string passes over a pulley, a distance L = 2.5 m away, and weights are hung from this end. Assume the string at the vibrator is a node, which is nearly true. The mass that must be hung from the end of the string to produce three loops of a standing wave is

A) 800 g.
B) 400 g.
C) 100 g.
D) 40 g.
E) 10 g.