Explanation:

The continents that form a mirror image of each other are Africa and South America.

Continental Drift:
The concept of continental drift states that the continents were once joined together in a single landmass called Pangaea and have since drifted apart. This theory was proposed by Alfred Wegener in the early 20th century.

Shape of the Continents:
If we look at the shape of the continents, we can observe that the eastern coast of South America and the western coast of Africa fit together like puzzle pieces. The fit is most apparent when we consider the continental shelves, which are the submerged parts of the continents that extend into the oceans.

Evidence:
1. Matching coastlines: The most obvious evidence for the continental fit is the similarity of the coastlines of Africa and South America. The shape of the eastern coast of South America matches the western coast of Africa, including the Gulf of Guinea and the bulge of Brazil.

2. Fossil evidence: Fossil evidence also supports the theory of continental drift. Fossils of the same plant and animal species have been found on both the eastern coast of South America and the western coast of Africa. For example, the Mesosaurus, a freshwater reptile, is found exclusively in these two regions.

3. Rock formations: The rock formations on both sides of the Atlantic Ocean also provide evidence for the continental fit. The rock types and ages match up across the ocean, indicating that they were once part of the same landmass.

4. Mountain ranges: The alignment of mountain ranges on both sides of the Atlantic further supports the idea of continental drift. For example, the Appalachian Mountains in North America are similar in age and structure to the Caledonian Mountains in Europe.

Conclusion:
Based on the evidence from matching coastlines, fossils, rock formations, and mountain ranges, it can be concluded that Africa and South America were once joined together and have since moved apart due to continental drift. This makes them a mirror image of each other.