1. The problem asks about the tone created by the poet's use of the words "liberty" and "freedom" in the poem "Icarus's Flight" by Stephen Dobyns. 2. Tone in literature refers to the attitude or feeling conveyed by the author through word choice and style. 3. The words "liberty" and "freedom" generally evoke feelings of seriousness and importance, as they relate to fundamental human rights and conditions. 4. Among the options given: Cautious, Frightening, Serious, the best answer is "Serious" because these words create a tone that is thoughtful and weighty. Final answer: Serious