Context: The map below shows air temperatures in the lower atmosphere on April 19, 2016. The outlined area shows an air mass that influenced weather in North America on that day.
Look at the map. Then, answer the question below.
Data source: United States National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Physical Sciences Division
Which air temperature was measured within the outlined area shown?
A. 3°C
B. -17°C
C. -4°C
Answer with the option's letter from the given choices directly.

B