With Regard to Restrictive Covenants

With regard to restrictive covenants:

A) even though they are not created by a governmental entity, if they restrict racial minorities' right to buy land they are unconstitutional.
B) they are generally legal even when they discriminate against the disabled in group homes since these homes do not contain "families" under the traditional
Meaning of the word.
C) they can only be used to restrict residential property, but not commercial.
D) all of the above.