A spherical conductor of radius $10\text{cm}$ has a charge of $3.2\times 10^{-7}\text{C}$ distributed uniformly. What is the magnitude of electric field at a point $15\text{cm}$ from the centre of the sphere?($\frac{1}{4\pi {ϵ}_0}=9\times 10^9{\text{N m}}^2{\text{/C}}^2$)

1. A
   $1.28\times 10^4\text{N/C}$
2. B
   $1.28\times 10^5\text{N/C}$
3. C
   $1.28\times 10^6\text{N/C}$
4. D
   $1.28\times 10^7\text{N/C}$