The correct answer is option 1: depth of the seabed.

SONAR stands for "Sound Navigation and Ranging". It is a technology used to detect and locate objects underwater by emitting sound waves and measuring the time it takes for the sound waves to bounce back.

Option 1 is correct because one of the main applications of SONAR is to determine the depth of the seabed or ocean floor. SONAR sends out sound waves that travel through the water and bounce off the ocean floor. By measuring the time it takes for the sound waves to return, scientists and researchers can calculate the depth of the seabed.

Option 2, intensity of an earthquake, is incorrect. SONAR is not used to measure the intensity of earthquakes. Earthquakes are generally measured using seismographs, which detect and record the vibrations caused by seismic waves.

Option 3, cruising altitude of an aircraft, is also incorrect. SONAR is not used in aviation to determine the cruising altitude of an aircraft. Aircraft altitude is typically measured using altimeters or radar-based systems.

Option 4, speed of a moving object, is also incorrect. SONAR is not used to measure the speed of moving objects. Instead, it is used to detect and locate objects underwater based on the time it