Which of the Following Is NOT an Example of an Endosymbiont

Multiple Choice

Which of the following is NOT an example of an endosymbiont?

A) Bacillus anthracis spores present in the soil of cattle farms
B) rhizobial bacteria growing in the root nodules of certain plants
C) microorganisms in the digestive system of the cow degrading cellulose
D) bacteria in termite intestines digesting plant polymers