Seasonal variations

Hi.
Plz can u help me with this question.Thanks

A company is preparing its forecast sales and purchase information for January of the next financial year.
The sales volume trend is to be identified using a 3-point moving average based on the actual monthly sales volumes for the current year.
Month Sales volume (units)
August 72,100
September 49,600
October 65,800
November 82,600
December 60,100
What is the seasonal variation for the month of November?

A 69,500 units
B -69,500 units
C -13,300 units
D 13,100 units