Explanation:

A multirange voltmeter is a measuring instrument used to measure voltage across different ranges. It is important for a voltmeter to have high and constant input impedance so that it does not draw significant current from the circuit being measured, thereby affecting the accuracy of the voltage measurement.

The options given are:
a) Permanent Magnet Moving Coil Voltmeter
b) Electronic Voltmeter
c) Moving Iron Voltmeter
d) Dynamometer Type Voltmeter

Permanent Magnet Moving Coil Voltmeter:
A permanent magnet moving coil (PMMC) voltmeter uses a coil suspended in a magnetic field to measure voltage. While it has a high input impedance, it is not constant across different ranges. As the range is changed, the coil resistance also changes, affecting the input impedance.

Moving Iron Voltmeter:
A moving iron voltmeter uses a movable iron vane to measure voltage. It has a lower input impedance compared to a PMMC voltmeter. Moreover, the input impedance of a moving iron voltmeter varies with the range, which makes it unsuitable for high and constant input impedance measurement.

Dynamometer Type Voltmeter:
A dynamometer type voltmeter uses a pair of fixed and moving coils to measure voltage. While it has a high input impedance, it is not constant across different ranges. The coil resistance changes with the range, affecting the input impedance.

Electronic Voltmeter:
An electronic voltmeter, also known as a digital voltmeter (DVM), is a type of voltmeter that uses electronic circuitry to measure voltage. It has high and constant input impedance across different ranges. The input impedance of an electronic voltmeter is typically in the order of megaohms, which ensures minimal loading effect on the circuit being measured.

Conclusion:
Among the given options, the electronic voltmeter is the only one that has high and constant input impedance. This makes it suitable for accurate voltage measurements without significantly affecting the circuit being measured.