______ of the total surface area of the earth is covered with water.

The correct answer is Option (3) → 70.8%

The Earth’s surface area is about 510 million km², and the oceans cover about 361 million km² of it: \(\frac{361}{510}\times100\approx70.8\%\). So about 70.8%, usually rounded to 71%, of the surface is covered with water, and the remaining 29% is land. This is why the Earth is called the “blue planet”.