Question #N478

The novel follows the lives of two sisters, Amelia and Beatrice, who are as different as night and day. Amelia is a bookish, introspective young woman, always lost in her thoughts, while Beatrice is vibrant and outgoing, a social butterfly who loves to be the center of attention. While they are vastly different, their bond is unbreakable, and they support each other through thick and thin.

Which choice best completes the sentence so that it conforms to the conventions of Standard English?
A. As they are vastly different, their bond is unbreakable, and they support each other through thick and thin.
B. As they are vastly different, their bond is unbreakable, and they support each other through thick and thin.
C. Although they are vastly different, their bond is unbreakable, and they support each other through thick and thin.
D. Because they are vastly different, their bond is unbreakable, and they support each other through thick and thin.