How Does the Theory of Planetary Migration in Disks Possibly

How does the theory of planetary migration in disks possibly account for the highly eccentric orbits discovered for some extrasolar planets?

A) When migrating planets pass close enough for a gravitational encounter, one may be flung from the system while the other is shifted to a highly elliptical orbit.
B) When migrating planets collide, they would move onto more eccentric orbits.
C) When a planet migrates onto the surface of the star, the additional stellar mass would disrupt the orbits of the remaining planets.
D) A migrating planet would create waves in the planet forming disk, which would in turn lead to the formation of planets on highly elliptical orbits.