A 20-Kg Mass Swings at the End of a Light String

Multiple Choice

A 2.0-kg mass swings at the end of a light string (length = 3.0 m) .Its speed at the lowest point on its circular path is 6.0 m/s.What is its kinetic energy at an instant when the string makes an angle of 50 $\degree$ with the vertical?

A) 21 J
B) 15 J
C) 28 J
D) 36 J
E) 23 J