①Astronomers have had difficulty accounting for certain planets discovered outside our solar system. ②They are called hot Jupiters because each is similar in mass to Jupiter, the largest solar-system planet, but orbits its parent star at a fraction of the distance at which Earth, let alone Jupiter, orbits the Sun. ③In the standard, solar-system-based theory of planetary formation, such a massive planet could not form so close to a star. ④So most attempts to explain a hot Jupiter’s existence envision it forming farther away, then migrating inward. ⑤According to one hypothesis, the planet’s gravitational field tugs on the protoplanetary disk of dust and gas from which it formed. ⑥The disk exerts its own gravitational tug, and this interplay of forces robs the planet of momentum in its orbital path, forcing it to spiral in toward the star. ⑦According to another hypothesis, the planet’s gravitational field is so strong that it creates a groove in the disk, partitioning it into inner and outer regions; the resulting gravitational interactions between the planet and these regions cause the planet to lose orbital momentum and spiral inward. ⑧Another question remains: what prevents the planet from continuing its spiral until it collides with the star?

3. It can be inferred from the passage that the “attempts” share which of the following goals?

A. to explain how a Jupiter-sized planet could form so close to its parent star.

B. to explain what prevents a hot Jupiter from colliding with its parent star.

C. to determine whether a hot Jupiter is formed from a protoplanetary disk of dust and gas.

D. to determine whether a hot Jupiter’s gravitational field is strong enough to create a groove in its protoplantary disk

E. to account for hot Jupiters in a way that is not inconsistent with the standard theory of planetary formation