TOEFL Listening: TPO-TOEFL阅读TPO - KRDWPFAGDCK9286UN$

According to paragraph 5, why are geologists unable to trace back the entire geologic of continents from hot-spot trails? A. Hot spots have existed for only about 5 percent of geologic time. B. Hawaii did not exist 50 millions years ago. C. Oceanic basins that contained old hot-spot trails disappeared a long time ago. D. Hot-spot trails can be reconstructed only for island chains.