Option 2 : 50%

Let the fruit seller purchase 100 mangoes in Rs. 100

Cost price of 1 mango = Rs. 1

He sells 50% of mangoes = 100 × 50% = 50 mangoes

At a profit of 50% of total cost.

So, profit = total cost × 50% = 100 × 50/100 = Rs. 50

∴ Selling price of 50 mangoes = C.P + Profit = 50 + 50 = Rs. 100

So profit % = 50/50 × 100 = 100%

He sells 50 mangoes at the profit of 100%

He sells 80% of the remaining mangoes = 80/100 × 50 = 40 mangoes

Cost price of 40 mangoes = Rs. 40

Selling price of 40 mangoes = 125/100 × 40 = Rs. 50

So overall cost price = Rs. 100 of 100 mangoes

Overall selling price = 100 + 50 = Rs. 150

So, profit = 150 - 100 = Rs. 50

Profit % = 50/100 × 100 = 50%