The topic Ivan Ilyich thinking about in this excerpt from Leo Tolstoy’s The Death of Ivan Ilyich is that there are two kinds of life: the artificial life and the authentic life. Artificial life is represented by Ivan, Peter, Praskovya and almost all the people in the society of Ivan - it is marked by shallow relationships and materialism. Authentic life is represented by Gerasim.
"D. orb" would be the proper answer. Orbs are circular objects, usually referring to artifacts. In this case, the orb is the giant eye in the forehead that moves within a socket.
