<em>dialog that subtly suggests communication conflicts</em> This is the correct option.
The charters in the story ,“Hills Like White Elephants”, talk about "it" all the time. The reader has to infer that what the man and the woman are talking about is an abortion. However, they seem to have difficulties to speak openly about it and they do not have it clear what they will decide. There are communication conflicts. The man thinks he knows what will be best for the woman but she does not sound so assertive. Their dialogue is fragmented. There is not a "history" line through it. The reader has to assume how it is they got together and she became pregnant. Yet, the couple are faced with a difficulty they find it hard to talk about.
These options are not right:
-characters who hide secret intentions from one another ( In this case, the woman is not hiding her pregnancy, for example. The man is not hiding his intentions , either. They cannot talk freely and openly about their problem: the woman 's pregnancy).
-imagery that highlights the importance of the setting. ( The imagery is used metaphorically to ,probably, represent the characters' emotions and moods).
-metaphors that reveal significant plot developments. ( Heminway tends to use simple language to get closer to the reader. Therefore, he will not oversuse sophisticated language).