The correct answer is: A. Parallel
A voltmeter is a device used to measure the potential difference (voltage) between two points in a circuit. It is connected in parallel with the circuit component across which the voltage is to be measured. This means that the voltmeter has two terminals, one connected to each of the points in the circuit. The current flowing through the circuit does not pass through the voltmeter, so it does not affect the measurement.
If the voltmeter were connected in series with the circuit component, the current would have to pass through the voltmeter. This would cause a voltage drop across the voltmeter, which would be in addition to the voltage being measured. This would make the measurement inaccurate.
Therefore, a voltmeter is always connected in parallel with the circuit component across which the voltage is to be measured.
Option B is incorrect because a voltmeter is not connected in series with the circuit component.
Option C is incorrect because a voltmeter is not connected in series or parallel with the circuit component. It is connected in parallel.
Option D is incorrect because a voltmeter is always connected in parallel with the circuit component across which the voltage is to be measured.