The idea that the continents were once one large landmass called pangaea is part of the theory of continental drift true or false

It is true. In the early 1900s, Alfred Wegener proposed the idea of Continental Drift. His ideas centered around continents moving across the face of the Earth. The idea was not quite correct - compared to the plate tectonics theory of today - but his thinking was on the proper track. Pangea is part of his theory!