How is the underlined gerund phrase used in the sentence?

flossing before bedtime is important for good dental

health.

a. predicate nominative

b. direct object

c. subject

d. object of a preposition

In paragraph 5, president obama remarks: “you know, when trayvon martin was first shot i said that this could have been my son. another way of saying that is trayvon martin could have been me 35 years ago.” how does president obama use rhetoric in this quote to contribute to the overall meaning of his speech?