TOEFL Reading: ETS-TOEFL阅读机经 - Y1R7IKUIKMX4IMS5L$

According to paragraph 6, which of the following is true about the Oort cloud? A. It is almost 10,000 times the size of the Sun. B. It is formed by the orbits of long-period comets orbiting far from the Sun. C. It is produced by the gravitational effects of distant stars. D. It can disrupt the orbit of a comet enough to send it on a path toward the Sun.