how does referring to the bacterial microbes as "friends" and "foes" contribute to the meaning in the passage?

It emphasizes the idea that bacteria can be both helpful and harmful.

Explanation: Bacterial microbes are essential to helping our bodies work, but also they can also harm us as well. Therefore C is correct.

Hope this helps!

Phillis Wheatley's poem 'To His Excellency General Washington' has a central theme of 'freedom's cause.' In the poem, Wheatley explains the struggles that the colonists had with pursuing freedom from England, which caused a civil war. Wheatley uses the term 'Columbia' to refer to America, represented the country as in the right for taking a stance against England. Wheatley uses the 'Celestial Choir' as a poetical type muse, which inspired her writing. Wheatley also has a description of the 'goddess of Freedom.' The goddess comes down from heaven in order to involve herself in the civil war between the colonists and Britain. The reference to 'olive branch' in the poem represents a symbol of peace.  Wheatley compares the battle forces of America to the Greek forces of Eolus, king of the winds. The simile Wheatley uses prepares the reader for the references to any military language that she used poetically such as, 'first in peace', to refer to Washington as the commander-in-chief of the army. By the end of the poem, Wheatley urges Washington to continue pursuing freedom for the colonists. She refers to the goddess of freedom as a guide for Washington. By the end, Wheatley believes that Washington will win and become the head of state. Themes of 'To His Excellency General Washington' include divine right and freedom.