Final answer:
In the stomach of a deceased cow, one could find grass or other food, a variety of bacteria and microbes, and digestive juices, specifically enzymes in the abomasum.
Step-by-step explanation:
When a cow dies, it's possible to find multiple substances within its stomach compartments. Among these substances are grass or food the cow was consuming before death, depending on the stomach chamber. Furthermore, there will be significant amounts of bacteria and other microbes that play a critical role in breaking down cellulose fiber through fermentation processes. Notably, digestive juices will also be present, particularly in the abomasum, which is the 'true' stomach where these enzymes are produced to digest food.
Ruminant animals like cows have a unique digestive system comprising four chambers: the rumen, reticulum, omasum, and abomasum. The rumen and reticulum contain prokaryotes and protists that help digest cellulose fiber. Upon death, these microbes continue to exist in the stomach until decomposition begins. Hence, all the options provided in the question are technically correct, but focusing on the main constituents typically responsible for digestion, bacteria, and digestive juices are the crucial elements present in the stomach of deceased cattle.