What Do Astronomers Think Is the Origin of the Many

What do astronomers think is the origin of the many irregular moons around the outer planets (irregular meaning they are orbiting backwards and/or have eccentric orbits) ?

A) These moons were likely formed elsewhere and captured by the giant planets
B) These moons are fragments of a much larger moon around each planet that exploded
C) These moons were expelled by volcanoes on the surfaces of the giant planets
D) These moons had an early interaction with the rings of the giant planets and were moved to strange orbits as a result
E) Astronomers have no idea about why these irregular moons exist; it's a complete mystery