Ammeter used to indicate temperature in an NTC thermistor?

Right, so as the diagram shows, this is an NTC thermistor. I got the ammeter and voltmeter reading part, but I don't understand the last question there. The mark scheme says the ammeter is used to detect the temperature... how exactly?

Well you want a meter where the reading goes up when the temperature goes up and down when the temperature goes down.
From your answer to the previous part, which of the two does that?

Alright, ammeter, definitely, yes... but how does getting a reading of 2 A or 4 A help me determine the exact temperature? The question says that the circuit is used to monitor the temperature...

Yes, but the question doesn't ask that.
It just asks which meter is used. Nothing more.
It doesn't ask you how this would be achieved.
In practice, if you wanted a scale on the meter to read temperature you would need to calibrate the meter by measuring the current at known temperature values.
As I say. The question isn't asking you this.