Answer: Option 'D' is correct.
Explanation:
Since we have given that
At 8:00 , the temperature was = 1.5°C.
that means Initial temperature = 1.5°C.
From, 8:00 to 11:00 , the temperature increased by = 0.7°C.
since it was increased , so we will use "Positive sign" to show the increment.
So, It becomes,

Again From 11:00 to 2:00 it dropped by = 2.6°C.
So, we will use "Negative sign " to show the reduction in temperature :
So, it becomes,

From 2:00 to 5:00 , it decreased by = 0.9°C.
again it will represented by negative sign.
So, it becomes,

Hence, Option 'D' is correct.