+1982 Chris found the average change of his stock portfolio over the following months: -9.23 in June, -7.13 in July, +31.50 in August, and +5.16 in September. Estimate the average change in his stocks by rounding to the nearest whole number.
A. +5 per month
B. +8 per month
C. +31.50 per month
D. +20 per month
