Explanation:

- Let's determine the area of the floor first. Cost is Rs9100 at a rate of Rs65 per m², so the total area is 9100 / 65 = 140 m².

- The ratio of the length to breadth is 7:5. Let length = 7x and breadth = 5x.

- So, area = length × breadth = 7x × 5x = 35x² = 140 m².

- Solving 35x² = 140, we find x² = 4, so x = 2.

- Length = 7x = 14 m, breadth = 5x = 10 m.

- Perimeter is given by 2(length + breadth).

- Thus, perimeter = 2(14 + 10) = 48 m.

- Therefore, the correct option is 48 m.