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. Spraying pesticides on a crop field — Yes. Agricultural drones are already used for precision spraying of pesticides and fertilizers over fields. Verdict: Correct.

2. Inspecting the craters of active volcanoes — Yes. Drones are used to fly into/over active volcanic craters to capture images, thermal data, and gas measurements where human access is risky. Verdict: Correct.

3. Collecting breath samples from spouting whales for DNA analysis — Yes. Small drones have been successfully used to collect whale blow samples for microbiome and DNA-related analysis without close human contact. Verdict: Correct.

Since all three activities can be carried out using drones at the present level of technology, the correct answer is (d) 1, 2 and 3.