Answer:
Option B.
Explanation:
From the graph during first six months average rainfall was
1st month - 2.91 inches
2nd month - 2.60 inches
3rd month - 3.86 inches
4th month - 3.19 inches
5th month - 3.46 inches
6th month - 3.27 inches
Now we have to calculate the mean of these rainfalls during six months
Mean =

=

=

= 3.215 inches
Therefore, mean of rainfall was 3.215 inches.
Option B is the correct option.