Explanation:

To determine the maximum selling price, let's evaluate each discount scheme on a marked price of 100 units.

- Scheme i: Two successive discounts of 15% each

- First discount: 100 * 0.85 = 85

- Second discount: 85 * 0.85 = 72.25

- Scheme ii: A discount of 25% followed by a discount of 5%

- First discount: 100 * 0.75 = 75

- Second discount: 75 * 0.95 = 71.25

- Scheme iii: Two successive discounts of 20% and 10%

- First discount: 100 * 0.8 = 80

- Second discount: 80 * 0.9 = 72

- Scheme iv: A discount of 30%

- Single discount: 100 * 0.7 = 70

The selling prices for schemes are:

- Scheme i: 72.25

- Scheme ii: 71.25

- Scheme iii: 72

- Scheme iv: 70

The maximum selling price is for Scheme i with 72.25 units.

The correct Answer is Option 4: Scheme i.