GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - Y7TAI75X0WC5DVNDJ

Which of the following elements is part of one but not both of the hypotheses discussed in the passage? A. an interplay of gravitational forces B. a loss of orbital momentum C. a protoplanetary disk composed of dust and gas D. a protoplanetary disk divided into two regions E. The movement direction of hot Jupiters