The correct option is A Rs. 25
Here, total number shares issued is Rs 80,00,000/Rs 100 i.e. 80,000. Final call was paid on 77,500 which makes total shares on which call was not received to 80,000-77,500 i.e. 2,500. Calls in arrears were Rs 62,500, therefore final call here will be Rs 62,500/2500 i.e. Rs 25.