Explanation:

Let’s break this down:

- The volume after melting equals the sum of the three original sphere volumes.

- Volume of a sphere: \(\frac{4}{3} \pi r^3\)

- Radii: 3 cm, 4 cm, 5 cm

- Total volume: \(\frac{4}{3} \pi (3^3 + 4^3 + 5^3) = \frac{4}{3} \pi (27 + 64 + 125) = \frac{4}{3} \pi (216) = 288\pi\)

- Let’s say final radius is \(R\).

- \(\frac{4}{3} \pi R^3 = 288\pi\)

- \(R^3 = 216\)

- \(R = 6\) cm

- Surface area of a sphere: \(4\pi r^2\)

- Original total surface: \(4\pi (3^2 + 4^2 + 5^2) = 4\pi (9 + 16 + 25) = 4\pi(50) = 200\pi\)

- New sphere: \(4\pi (6^2) = 4\pi (36) = 144\pi\)

- Diminution: \(\frac{200\pi - 144\pi}{200\pi} \times 100 = \frac{56}{200} \times 100 = 28\%\)

So here’s what matters:

- Option 1: 25% — not correct, too low.

- Option 2: 26% — close, but not exact.

- Option 3: 27% — still just shy.

- Option 4: 28% — Completely correct.

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