Understand the concept of electric field inside a uniformly charged sphere.

For a uniformly charged sphere, whether it is a conductor or a non-conductor with uniform volume charge density, the electric field at its center is zero. This is due to symmetry. For every small charge element creating an electric field vector pointing away from the center, there is an equal and opposite charge element on the diametrically opposite side creating an electric field vector that cancels it out.

• If the sphere is a conductor, all the charge resides on its surface. The electric field inside a conductor in electrostatic equilibrium is always zero.
• If the sphere is a non-conductor with uniform volume charge density $\rho$, the electric field at a distance $r$ from the center is given by $E = \frac{1}{4\pi\epsilon_0} \frac{Qr}{R^3}$ for $r \le R$. At the center, $r=0$, so the electric field $E = \frac{1}{4\pi\epsilon_0} \frac{Q(0)}{R^3} = 0$.

In both cases, the electric field strength at the center of a uniformly charged sphere is zero.

The options are:
(1) $\frac{Q}{4\pi\epsilon_0 R^2}$ (This is the field at the surface)
(2) $\frac{Q}{4\pi\epsilon_0 R}$
(3) $\frac{Q}{4\pi\epsilon_0 R^3}$
(4) Zero

The correct option is (4).

The final answer is $\text{(4)}$.