The correct answer is: B. low
The resistance in the circuit of the moving coil of a dynamometer wattmeter should be low. This is because the moving coil is a current-carrying conductor, and the current through it will cause a voltage drop across the resistance. This voltage drop will add to the voltage drop across the load, and will therefore affect the reading of the wattmeter. If the resistance is low, the voltage drop across it will be small, and the reading of the wattmeter will be more accurate.
Option A is incorrect because if the resistance is almost zero, then the voltage drop across it will also be almost zero. This means that the current through the moving coil will be very large, and the wattmeter will be damaged.
Option C is incorrect because if the resistance is high, then the voltage drop across it will be large. This means that the current through the moving coil will be small, and the wattmeter will not be able to measure the power accurately.
Option D is incorrect because the resistance in the circuit of the moving coil of a dynamometer wattmeter must be low.