Two Blocks of Masses 20 Kg and 9

Multiple Choice

Two blocks of masses 20 kg and 9.0 kg are connected together by a light string and rest on a frictionless level surface.Attached to the 9.0-kg mass is another light string,which a person uses to pull both blocks horizontally.If the two-block system accelerates at 0.80 m/s²,what is the tension in the second string attached to the 9.0-kg mass?

A) 23 N
B) 14 N
C) 16 N
D) 7.2 N
E) 25 N