Which of the following instruments would be most appropriate in comparing the air pressure at different places in the habitat?

Analyze the question: The question asks which instrument is best for comparing air pressure at different places in a habitat.

Explain the concept: Each instrument measures a different environmental factor:

• Hygrometer: measures humidity (moisture in the air).
• Barometer: measures atmospheric (air) pressure.
• Photometer: measures light intensity.
• Air pressure disc: this is not a standard ecological instrument for measuring air pressure. It is a distractor.

Step-by-step solution:

1. The factor we want to measure is air pressure.
2. The standard instrument for measuring atmospheric pressure is the barometer.
3. A hygrometer measures humidity, and a photometer measures light, so neither fits.
4. "Air pressure disc" sounds plausible, but it is not a recognised measuring instrument in ecology or physics.
5. Taking readings with a barometer at different spots in the habitat lets you compare the pressure at each place.

Answer: B. Barometer.

Exam tip: Match the instrument to the factor it measures:

• Barometer → Pressure
• Hygrometer → Humidity
• Photometer → Light
• Thermometer → Temperature
• Anemometer → Wind speed
• Rain gauge → Rainfall

If an option name looks invented, like "air pressure disc," be suspicious and go with the standard instrument.