1. in "a shocking accident," when greene writes about jerome’s father being killed by a falling pig, he is using humor of

situation
character
language

Explanation:

The premise of the short story is that it is feasible for an individual to bite the dust in a ludicrous manner which is really interesting like getting slaughtered by a falling pig, which isn't acceptable socially.  

In the story, Jerome's father gets murdered in an accident, yet this is by all accounts interesting to the general population. It gets offending for him and ludicrous as individuals don't trust it and make of it, so he chooses to conceal reality about the genuine reason for the mishap.

the underline word is basically like a prepositional phrase.