21. According to Alfred Wegener, which evidence does NOT shows that continents were once connected in
one giant supercontinent called Pangaea?

a. The coastlines of the continents appear to it together like the pieces of a puzzle.

b. Identical fossils have been found in the rocks on either side of the ocean.

c. Earthquake waves travel at a different speed in materials of different densities.

d. Coal has been found in cold regions​