Identical Point Charges (+20 $\mu$ C)are Placed at the Corners of an Equilateral Triangle with of an Equilateral

Multiple Choice

Identical point charges (+20 $\mu$ C) are placed at the corners of an equilateral triangle with sides of 2.0-m length.How much external energy is required to bring a charge of 45 $\mu$ C from infinity to the midpoint of one side of the triangle?

A) 26 J
B) 16 J
C) 23 J
D) 21 J
E) 12 J