Current cannot flow to ground through
(A) A mechanical ground
(B) An Ac ground
(C) A virtual ground
(D) An ordinary ground

Hint: We know that the flow of current in a circuit starts from a battery or cell or any other source of voltage, this source of voltage passes current into the circuit due to the voltage differences it possesses. So, flow of current in the circuit is due to voltage difference.

Complete Answer:
We know that the potential differences are relative and are measured with respect to a common reference point, usually the point is the ground. This is because the ground is a basin of charges and still is neutral since it does not emit any charges directly. And we also know that all our homes have a circuit that is grounded. The reason for grounding circuits is to neutralize the excess charges which might cause harm to your circuit. The extra harmful charges are transferred into the ground.
So, we know that the charges can be transferred to the ground. Out of the given options,
A mechanical ground is the process of grounding the electric connections to a mechanical body that is preferably neutral or does not give away excess number of charges. The most efficient and perfect mechanical ground is the earth itself. Thus, we know current can flow through mechanical ground.
An AC ground is the surface that is used for grounding AC current circuits. As necessary is grounding for any object, we do not use earth in AC grounding, but other circuits can allow current to flow through an AC ground. Hence, we know the second option fails.
A virtual ground in electronics is defined as a node of circuit that is maintained at a steady reference potential, without being directly connected to the reference potential. This means that charges should be allowed to pass through a virtual ground. And hence we know that current cannot flow through a virtual ground, unlike the other options given.
Hence the correct answer is option C.

Note:
Grounding is an essential process in any sector involving electronics and electricals. It is majorly done out of concern about your safety and your appliances’ safety. Any abnormalities in the circuits can cause an electric shock which can be avoided by grounding and directing these charges into the ground.