Two Boxes Are Connected to Each Other by a String

Multiple Choice

Two boxes are connected to each other by a string as shown in the figure.The 10-N box slides without friction on the horizontal table surface.The pulley is ideal and the string has negligible mass.What is true about the tension T in the string?

A) T = 10 N
B) T = 20 N
C) T = 30 N
D) T < 30 N
E) T > 30 N