There are so many examples for that in different areas, like biology experiment carried out in our lab recently.
Here's one link: https://www.creative-biogene.com/Services/Custom-Viral-Service/Replication-Competent-Virus-Testing.html
Yes, decomposers have predators. A worm is a decomposer, but it's predator is birds.
Also, it is made up of water and contains enzymes, organelles, salts and various organic molecules. Furthermore, cytoplasm functions by supporting and suspending organelles and cellular molecules. However, example of cytoplasm includes: mitochondria, ribosomes while nucleus is an example of non-example of cytoplasm.
The answer is A, 'a mammal' because it goes with the copulative verb 'to be', i. e., 'is'.