Consider the following activities:1.Spraying pesticides on a crop field2.Inspecting the craters of active volcanoes3.Collecting breath samples from spouting whales for DNA analysis. At the present level of technology,which of the above activities can be successfully carried out by using drones?

1. A

   1 and 2 only

   1 and 2 only. Whale breath sampling by drone was already demonstrated.

2. B

   2 and 3 only

   2 and 3 only. Crop spraying by UAV is routine.

3. C

   1 and 3 only

   1 and 3 only. Volcano crater inspection is also a drone job.

4. D

   1, 2 and 3

   All three. Pesticide UAV, volcanic crater flights, and cetacean blow sampling — all done at the then tech level.

Summary. Official key is (d) 1, 2 and 3. Drones already sprayed fields, inspected active craters, and collected whale breath for DNA. None of the three was science fiction in 2020.