Have doubt regaring Gross Sales question

Consider the following data pertaining to CAS Ltd. For the month of march 2023:
Opening stock 60,000,
Closing stock 80,000,
Purchases 11,20,000,
Returns outwards 30,000,
Return inward 40,000,
Carriage inward 10,000.
If the gross profit is 20% of the net sales, the gross sales for the month of march 2023 is:
A.13,80,000.
B.13,50,000.
C.10,80,000.
D.13,37,500.
What is the correct answer??
The author in the book has marked option A as answer, but I feel it's wrong. Can anybody solve this ? my answer is 13,90,000.