Appearance of resistant organisms in a time scale of months or years, by the excessive use of antibiotics is an example of which of the following?

Evolution by anthropogenic action

The correct answer is Option (3) → Evolution by anthropogenic action

The development of antibiotic-resistant organisms is a clear case of evolution by anthropogenic action, which means evolution driven by human activities.

Use of Antibiotics: When antibiotics are used to treat infections, they kill most of the bacteria. However, a few bacteria may survive if they have or acquire mutations that make them resistant to the antibiotic.The surviving bacteria reproduce and pass on their resistance genes to the next generation. Over time, the number of resistant bacteria increases because they have a survival advantage in an environment where the antibiotic is present.

The overuse or misuse of antibiotics by humans in medicine, agriculture, and livestock farming accelerates this process. This human-driven (anthropogenic) action creates a strong selective pressure, pushing the evolution of resistant strains.