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?

The correct option is 1, 2 and 3.

At the present level of technology, unmanned aerial vehicles (UAVs), commonly known as drones, have evolved significantly and are successfully deployed across various agricultural, environmental, and scientific domains. Below is a detailed explanation of how drones are utilized for each of the listed activities:

1. Spraying pesticides on a crop field:
Drones equipped with specialized spraying nozzles, reservoirs, and GPS-guided navigation systems are widely used in precision agriculture. They can fly autonomously over crop fields to distribute liquid pesticides, fertilizers, or herbicides. This method is highly efficient as it allows targeted application, reduces water and chemical waste, and prevents agricultural workers from direct exposure to hazardous chemicals.

2. Inspecting the craters of active volcanoes:
Volcanic craters are highly hazardous environments for researchers due to extreme heat, toxic gas emissions, and unpredictable eruptions. Drones equipped with thermal cameras, gas sensors, and high-definition imaging systems are deployed to fly directly into or over active volcanic craters. They gather real-time data, monitor structural changes, and measure gas concentrations without risking human lives.

3. Collecting breath samples from spouting whales for DNA analysis:
Marine biologists use customized drones to study whale health non-invasively. When a whale surfaces and blows (spouts) a mixture of mucus, air, and water, a drone is flown through the spray to collect samples on sterile petri dishes or collection plates. These samples contain blow-hole discharges rich in DNA, hormones, and microbiomes, which are then analyzed in laboratories to monitor the whale's health, stress levels, and genetic profile without capturing or disturbing the animal.

Since all three activities are currently feasible and successfully performed using drone technology, the correct option is 1, 2 and 3.