A charged ring of radius 0.5 m has a 0.002 πm gap. If the ring carries a charge of +1 C, the electric field at the center is:

A. 7.5×10⁷ NC−¹
B. 7.2×10⁷ NC−¹
C. 6.2×10⁷ NC−¹
D. 6.5×10⁷ NC−¹