Exp) Option b is the correct answer.

Radars use radio waves to detect and locate objects by transmitting pulses and analyzing the reflected signals. They measure distance, speed, and direction, playing a vital role in aviation, maritime navigation, weather forecasting, and military applications. Radars enable precise tracking and surveillance over long distances and in various conditions.

Statement 1 is incorrect: X-ray machines and metal detectors are used at airports and not radar based detectors. Thus, radars are not used for identification of narcotics on passengers at airports or in aircraft.

Statement 2 is correct: Radars are extensively used for monitoring of precipitation. Weather radars (specifically Doppler radars) are instrumental in monitoring and tracking precipitation, measuring the intensity of rainfall, and predicting weather patterns.

Statement 3 is correct: Radars can be used to track the migration of animals, particularly birds and bats. Radar technology helps in monitoring flight patterns and migration routes of these animals over large distances.

Source: https://www.nationalguard.mil/News/Article/572811/stopping-drug-traffickers-by-air/

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/meteorological-radar#:~:text=Weather%20radar%20observation%20can%20be,radar%20observations%20(Figure%2010),https://www.usgs.gov/centers/national-innovation-center/science/new-wildlife-tag-enabling-animal-tracking-using-weather