Answer:
Barometer
Step-by-step explanation:
Since the pressure is the thing which needs to be measured, a thermometer would be useless as it measures the temperature, not the pressure. A calorimeter measures the heat of a reaction (again, through the temperature change), so a calorimeter is useless. a barometer measures pressure, so a barometer should be chosen. the last option measures some sort of light, which again, doesn't measure pressure.