Bacteria Can Be Beneficial in Which of the Following Ways

Bacteria can be beneficial in which of the following ways?

A) They can be used to clean up an oil spill in a process called bioremediation.
B) They can be used in industry to generate products, particularly in food processing.
C) They are present on the skin and help crowd out harmful bacteria.
D) They function in wastewater purification to remove both organic and inorganic substances.
E) All of the answer choices describe ways that bacteria can be beneficial.