We need to consider some context from the novel when trying to answer this question. Until Victor succeeded in creating the Creature, he was obsessed with the idea of creating life. However, when faced with a living, breathing creature, Victor is repulsed by the "thing" he has created, making him flee. This, in turn, massively impacts the Creature's own feelings about humanity. He doesn't understand why people flee until he sees himself in a stream and realizes that he is ugly by society's standards. It is also because of this that he will never be accepted into society or find a mate. He sees himself as difficult to love because no one can look on him. This is why he gets on so well with the blind man. It is only when his children return that the Creature is forced to leave.
With this in mind, choice D is the best answer here. Throughout the novel, he is continually isolated from those around him, even when he seeks to prove that he is intelligent and gentle, not the monster that he looks like. Choices A and B do not create sympathy in the readers because he has committed terrible crimes. It is only through the Creature's perspective that we can truly understand the struggle he has. It is also because of this that Choice C would be a good answer, except just because someone is intelligent does not make them sympathetic.