Astronomers Believe That the "Hot Jupiters" Found Orbiting Other Stars

Astronomers believe that the "hot Jupiters" found orbiting other stars must have migrated inward over time

A) by slowly accreting large amounts of gas and increasing their gravitational pull.
B) by losing their gas because of evaporation.
C) by losing orbital angular momentum.
D) after colliding with another planet.
E) after a close encounter between their star and another star.