Ismene is Antigone's sister. Although her values and moral compass are similar to those of Antigone, she is a lot less brave, which leads her to make worse decisions out of cowardice. Ismene is a lot more reluctant than Antigone to go against the law as she is fearful of human authority. Therefore, she refuses to bury her brother, which Antigone eventually does. Ismene is also driven by a desire to achieve peace. She believes that, since their family has already suffered enough, they should try to avoid conflict. This is not a view Antigone can endorse.
A best supports the argument because it is the only answer that describes the pros of having mice as pets, while the others provide tips and facts upon adopting them.