18. A long straight very thin wire on the y-axis carries a 10-A current in the positive y-direction. A circular loop 0.50 m in radius, also of very thin wire and lying in the yz-plane, carries a 9.0-A current, as shown. Point P is on the positive x-axis, at a distance of 0.50 m from the center of the loop. What is the magnetic field vector at point P due to these two currents? (μ0 =4πx 10-7 T m/A) (A) zero (B) -8.0 x10-6Tk (C)(+4.0x10-6T)i- (4.0 x10-6T)k (D) (-8.0x10-6T)i - (8.0 x 10-6T)k (E)(-4.0x10-6T)i-(4.0 x10-6T)k