Darwin's finches are the example of:

Adaptive radiation

The correct answer is Option (4) → Adaptive radiation

During his journey, Darwin visited the Galapagos Islands, where he observed an incredible diversity of creatures. He was particularly fascinated by small black birds, which were later named Darwin's Finches. He realized that there were many varieties of finches in the same island. All the varieties, he conjectured, evolved on the island itself. From the original seed-eating features, many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches . This process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation. Darwin’s finches represent one of the best examples of this phenomenon. Another example is Australian marsupials.