CORRECT
Object D is unique because it is the
only one without a singular distinction.
Object A is the only one with a blue border and X.
Object B is the only one with a round border.
Object C is the only one with a pink interior.
Object E is the only one that is tilted.
Object D and others have a maroon
square border.
Object D and others have a maroon X.
Object D and others have a yellow interior.
Now, this decision is based upon my perspective. I can easily understand why you would pick any of the other objects - they each have a noticable difference in some aspect. It's all a matter of opinion.