Answer: Option 'A' is correct.
Step-by-step explanation:
Since we have given that
At noon, the temperature was = -3 degrees
Temperature reduced by = 2.5 hours per day
Temperature reaches = -18 degrees
Let the number of hours be 'x'.
According to question,
[tex]-3-2.5x=-18\\\\-2.5x=-18+3\\\\-2.5x=-15\\\\x=\dfrac{15}{2.5}=6[/tex]
Hence, it will take 6 hours for the temperature to reach.
Option 'A' is correct.