Why Do We Expect WIMPs to Be Distributed Throughout Galactic

Why do we expect WIMPs to be distributed throughout galactic halos, rather than settled into the galaxy's disk?

A) WIMPs annihilate when they come into contact with ordinary matter, such as stars.
B) WIMPS cannot produce photons, therefore they rarely interact and exchange energy with other particles.
C) Shock waves from generations of supernovae have blown the WIMPs out into the halo.
D) WIMPs are light enough that they have expanded out into the halo.
E) WIMPs were produced in the early stages of galaxy evolution, and objects in the halo, such as globular clusters, were formed first.