The correct answer is A. Current will flow to earth.
When a live conductor of public electric supply breaks down and touches the earth, a current will flow from the conductor to the earth. This is because the earth has a much lower resistance than the conductor, so the current will take the path of least resistance. The flow of current will cause the earth to become energized, and anyone who touches the earth will receive an electric shock.
Option B is incorrect because the supply voltage will not drop. The supply voltage is determined by the power supply, and it is not affected by the current flowing to the earth.
Option C is incorrect because the supply voltage will not increase. The supply voltage is determined by the power supply, and it is not affected by the current flowing to the earth.
Option D is incorrect because current will flow in the conductor. The current will flow from the conductor to the earth because the earth has a much lower resistance than the conductor.