GRE Reading Comprehension: ETS-GRE阅读ETS - 4HRCLY477I8672A77

According to the passage, it is believed that oceanic islands are formed from A. the same material as mantle xenoliths B. the same material as the midocean ridge system C. volcanic rocks from the upper mantle D. incompatible elements percolating up from the lower mantle E. mantle plumes arising from the lower mantle