Consider the following activities: 1. Identification of narcotics on passengers at airports or in aircraft 2. Monitoring of precipitation 3. Tracking the migration of animals. In how many of the above activities can the radars be used?

1. Identification of narcotics on passengers at airports or in aircraft — This is not a standard use of radar. Airport security uses X-ray scanners, CT scanners, trace detectors, sniffer dogs, etc.; radar is for detecting objects/position/motion, not reliably identifying narcotic substances. Verdict: Cannot be used.

2. Monitoring of precipitation — Weather radar is routinely used to detect rainfall, snowfall and storm structure. Verdict: Can be used.

3. Tracking the migration of animals — Radar is used to track migration of birds, bats and even insect swarms. Verdict: Can be used.

Hence, only two activities (2 and 3) can use radar, so the correct answer is (b).