Consider the following activities : 1. Spraying pesticides on a crop field 2. Inspecting the craters of active volcanoes 3. 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. Activity 1 (Spraying pesticides on a crop field): This is a well-established application. Agricultural drones equipped with tanks and spray nozzles are widely used for precision spraying of pesticides, fertilizers, and herbicides, offering efficiency and reduced human exposure. This can be successfully carried out. 2. Activity 2 (Inspecting the craters of active volcanoes): Drones equipped with cameras (visual, thermal) and gas sensors are increasingly used by volcanologists to monitor active volcanoes safely from a distance. They can fly into hazardous areas like craters to gather data. This can be successfully carried out. 3. Activity 3 (Collecting breath samples from spouting whales for DNA analysis): Specialized drones (like the 'SnotBot' project) have been developed to fly through the blow exhaled by whales (spouting) and collect the respiratory vapour (breath samples) on petri dishes. These samples contain biological material, including DNA, hormones, and microbes, useful for analysis without disturbing the animals. This can be successfully carried out. 4. Therefore, at the present level of technology (as of 2020), all three activities can be successfully carried out using drones.