None of the above. It has only one stomach that is divided into four different chambers.. It's very popular to think it has four stomachs, but this popular misconception is just that: a misconception.
A cow's diet is much harder to digest than that of an omnivore's or carnivore's diet. Thus it requires several steps in order for a cow (being a ruminant) to fully digest and absorb the nutrients...
The names of each of the chambers of a cow's stomach, in order from front to back, are as follows: Reticulum Rumen Omasum Abomasum See the related question below for more information.