Answer: The right answer is the 4) He has a deep affection for Amphimedon.
Explanation: Just to elaborate a little on the answer, it can be added that it is possible to infer that Agamemnon seems surprised, and very afflicted, to see him in the Underworld. After all, Amphimedon is the son of his younger brother Melenaus - note that he says "I am of yours." After having wondered what could have happened to him (did he die at sea during a storm, at the mainland stealing cattle, or in a fight?), he refers to him as "guest and friend." Earlier on he mentions his youth ("and so young") and praises him ("one could not better choose the kingdom's pride"), so, on account of those comments, it is possible to conclude that Agamemnon has a deep affection for Amphimedon. Agamemnon talks to Amphimedon.