Charge on a conducting metal sphere is present:

The correct option is: on the surface of the sphere

To understand why this is correct, we can analyze the behavior of charges in a conductor:
1. Nature of Conductors: In a conducting metal sphere, charges (specifically, free electrons) are free to move throughout the material.
2. Mutual Repulsion: Like charges repel each other. When extra charge is placed on a conducting sphere, the charges experience electrostatic repulsive forces from one another.
3. Maximizing Distance: To minimize their potential energy and the repulsive forces, the charges move as far apart from each other as possible. In a three-dimensional object like a sphere, the configuration that allows the charges to be at the maximum possible distance from one another is on the outer boundary or surface.
4. Electrostatic Equilibrium and Gauss's Law: Once the charges reach equilibrium, they stop moving. This means the electric field inside the conductor must be zero:

$$E_{\text{inside}}=0$$

According to Gauss's Law, the net electric flux through any closed surface is proportional to the enclosed charge:

$$\oint E·dA=\frac{q_{\text{enclosed}}}{{\epsilon }_0}$$

If we draw a Gaussian surface anywhere inside the metal sphere (just below the outer surface), the electric field is zero everywhere on that Gaussian surface. Therefore, the net enclosed charge must also be zero:

$$q_{\text{enclosed}}=0$$

This mathematical result proves that there can be no net charge inside the volume of the conductor. All excess charge must reside entirely on the outer surface of the conducting metal sphere.