One aspect of the characters to study in order to decipher the theme of the story is a. change over time b. appearance c. geographic location d. motivation

I would say A.) Change over time.

It could be 1, 2, or 4, depending on the context.1.) they could have had a fight, and she is too humble to say anything further. she wants robert to say something first.2.) maybe he's staring at a computer playing tetris while she's wearing a *really* tight red dress. just sayin' xd3.) is unlikely given that it's only one sentence worth of context long. 4.) it's possible their relationship is more 'mutual hatred' and they tolerate one another.it could be 1, 2, or 4, as long as you can provide sufficient explanation why. remember this as you write!