Explanation:

Let's break down the question step by step:

- Total students = 500

- Dancing students = 20% of 500 = 100

- Boys : Girls = 3 : 7

- Boys in Dancing = (3/10) × 100 = 30

- Girls in Dancing = (7/10) × 100 = 70

- Remaining students = 500 - 100 = 400

- Let Singing = x, Photography = y

- y = 0.6x

- x + y = 400 ? x + 0.6x = 400 ? 1.6x = 400 ? x = 250, y = 150

- Singing students = 250

- Photography students = 150

- Girls in Singing = Boys in Singing - 50

- Boys + Girls = 250

- Girls = Boys - 50

- Boys + Boys - 50 = 250 ? 2Boys = 300 ? Boys = 150, Girls = 100

- Boys in Photography = B, Girls in Photography = 0.875B

- B + 0.875B = 150

- 1.875B = 150 ? B = 80, Girls = 70

Now, the percentage asked is:

- (Girls in Singing) / (Boys in Photography) × 100 = 100 / 80 × 100 = 125%

So, the correct answer is:

Option 4: 125%

Summary of all statement interpretation:

- 500 total, 100 in Dancing (30 boys, 70 girls).

- 250 in Singing (150 boys, 100 girls).

- 150 in Photography (80 boys, 70 girls).

- Girls Singing (100)/Boys Photography (80) = 125%.

Correct answer: Option 4, 125%