Final answer:
The presence of glacial grooves in Africa is explained by Alfred Wegener's theory of continental drift, which suggests that the continent was once located closer to the South Pole as part of the supercontinent Pangaea, before drifting to its current warmer location.
Step-by-step explanation:
The discovery of glacial grooves in Africa, which is predominantly warm today, is indeed surprising. However, the hypothesis of continental drift, proposed by German meteorologist Alfred Wegener, helps to explain this geological phenomenon. According to Wegener's theory, continents were not always in their current positions but have drifted apart over geological time.
Among the four options provided to explain the glacial grooves in Africa, the most plausible is Option 3: Africa must have at one time been located closer to the South Pole. It has since drifted to its present location, farther from the South Pole, through the process of continental drift. This hypothesis is supported by Wegener's evidence, which includes the fit of the continents, similar fossils on now-distant lands, and paleoclimate evidence suggesting past positions of continents near the poles.
Wegener's idea of a supercontinent called Pangaea, where all continents were once joined, further corroborates that Africa, like other continents, was once part of this massive landmass and thus could have been situated in a region conducive to glaciation.