What are the differences among autobiography and Memoir?

Below is the last stanza of a poem, "dover beach," written in 1876 by matthew arnold. ah, love, let us be true to one another! for the world, which seems to lie before us like a land of dreams, so various, so beautiful, so new, hath really neither joy, nor love, nor light, nor certitude, nor peace, nor for pain; and we are here as on a darkling plain swept with confused alarms of struggle and flight, where ignorant armies clash by night. which of these statements best describes the remedy arnold proposes for the world? a. look to your dreams for answers to life's questions. b. our faith in each other can shelter us from deceptive chaos. c. in this deceptive world, ignorance requires faith. d. the world may end, but love conquers all.