Answer:
the amount of water vapor in the air
Explanation:
That's the amount of water vapor in the air that represents BEST the definition of humidity and what causes our sensation of the temperature to vary based on it.
That's why wet tropical forests are much more humid than arid dry deserts.
The other sentences are expressions of phenomenons that take place at various humidity levels, in various circumstances. When the humidity is very high, it will most likely cause storms and rain will fall.
B. The Outback.
The Outback is the correct word.
