The average monthly temperatures for the city of Mathville are given in the chart above. One year, January's average temperature was 7 degrees warmer, February's was 3 degrees cooler, June's was 2 degrees cooler, August's was 3 degrees warmer, and November's was 7 degrees warmer. What did this do to the average yearly temperature?
A) The average remained the same.
B) The average increased by 1°.
C) The average decreased by 1°.
D) The average increased by 17°.