Two particles are fixed to an x axis: particle 1 of charge ( -5.91 × 10⁻7 , C ) is at the origin and particle 2 of charge ( 5.91 × 10⁻7 , C ) is at ( x₂ = 20.8 ) cm. Midway between the particles, what is the magnitude of the net electric field? a. ( 1.39 × 10⁶ , N/C ) b. ( 2.78 × 10⁶ , N/C ) c. ( 4.17 × 10⁶ , N/C ) d. ( 5.56 × 10⁶ , N/C )