Providing you own the option or the copyright at the time of submission the project is eligible for entry.
Beyond that we cannot open or look at any contracts or comment further in a legal sense.
Beyond or outside of the above you would need to be satisfied that you do indeed own the option or rights and that - at the time of submission - you could conceivably exploit and execute said rights.
Of course, past that point we are not in control or involved in what you do, but clearly it is preferable that you own the rights to the original material when the contest closes for entries, and when the winners are announced.