How Does the Park Go Out of Control?

Well the title already says it. How does this park go out of control? I have a theory that is loosly based off a potential leak a while back. I don't know what it was exactly but it said something about how they don't feed the D-Rex live food due to if it was fed living food, then it would never eat dead food again.

So in the potential leaked trailer (this shouldn't be that much of a spoiler) we see the D-Rex eating a worker in what lloks like the D-Rex's enclosure. Now if we go off the "We don't feed it live food" thing then we an assume that either

A) The worker stumbled or got trapped in the pen and was eaten by the D-Rex, causing it to want more live food, which makes it break out and cause a large death toll.

B) The D-Rex already eats dead food but decides it wants to eat more humans instead of goats or cows. Thus making it escape and then cause a large death toll.

C) None of this is true and this is all just speculation that isn't true. Then the D-Rex cuases a large death toll.

What are your thoughts? Remember, this is just based off possible leaks. None of what I am saying is confirmed and can only be speculated about.