A radar of power 1 kW and is operating at a frequency of 20 GHz. It is located at a height of 1 km on a mountain. The maximum distance up to which it can detect object located on the surface of earth (Radius of earth = $6.4 × 10^6 m$) is:

113 km 11.3 km 1130 km 100 km

113 km

The correct answer is Option (1) → 113 km