In the poem "Love Songs," the speaker uses the phrases "black silence" and "shower of sunlight" in the first stanza and "the dark" and "clean swift brightness" in the second stanza. These contrasting phrases are most likely used to _____ .

a. share how day and night keep nature in balance
b. illustrate the clarity of life when time is taken to reflect
c. explain the conditions of human life as darkness and light
d. describe how pleasant memories have brightened life