question: Hint: Please answer the question requiring a floating-point number with two decimal places and provide the final value, e.g., 1.23, 1.34, 1.45, at the end.
  Question: In Fig. 21-25, the particles have charges $q_1=-q_2=100 \mathrm{nC}$ and $q_3=-q_4=200 \mathrm{nC}$, and distance $a=$ $5.0 \mathrm{~cm}$. What is the $x$ component of the net electrostatic force on particle 3?
  Choices:
  (A) 0
  (B) 0.34
  (C) 0.17
  (D) 3