Final answer:
c. The plate tectonics theory took decades to be accepted because scientists needed more evidence and a clear mechanism to explain continental drift.
Step-by-step explanation:
c. The plate tectonics theory took decades to be accepted primarily because scientists needed more evidence and a clear mechanism to explain how continents could drift over thousands of miles.
Alfred Wegener, who proposed the idea of continental drift in 1915, had put forward arguments like the fitting of continents, matching fossils and mountain ranges, and paleoclimate evidence. However, the lack of a well-developed hypothesis for the mechanism hindered the acceptance of Wegener's idea initially.