(2013? Suqian Second Model) As shown in the picture is the schematic diagram of the grip dynamometer, in which the upper end of the spring and the sliding rheostat slide are fixed together, and there

(2013? Suqian Second Model) As shown in the picture is the schematic diagram of the grip dynamometer, in which the upper end of the spring and the sliding rheostat slide are fixed together, and there is a retractable part between AB

Because when the grip force F increases, the slider slides downward, the resistance of the connected circuit increases, and the total resistance increases accordingly.

According to Ohm's law, it can be seen that in the circuit As the current becomes smaller, the voltage across R0 decreases;

According to the fact that the total voltage of the series circuit is equal to the sum of the voltages of each branch, it can be seen that the voltage across the sliding rheostat becomes larger, that is, the indication of the voltmeter becomes larger.

So choose A.