MA doubts

Question.
Company X used absorption costing and absorbs overheads on a per unit basis.
In the last period when company X sold 19800 units, budgeted production overheads were £170000 and there was an under absorption of £ 10000. Opening inventory was 1300 units and closing inventory was 1500 units. What was the overhead absorption rate used by company X

Choose the right option.
Option A- 8.08
Option B- 8
Option C- 8.50
Option D- 9