It's best to start with whether or not the question is answerable before trying to answer it. First, it depends on what you mean by answerable: 1. You could mean is there something in the world which is the cause of this; 2. You could mean is this cause in the world something that could be described by a human being; 3. You could mean is it possible for a human being to discover this thing and then describe it; 4. You could mean is it possible for a human being to prove to himself or someone else that he has discovered it and has correctly described it.
Regarding question 1: If the answer to this is not yes, then there really doesn't seem to be a point to any human inquiry because our minds assume that a generalized principle in the universe like this must have a cause. Regarding 2 and 3, I don't assume that humans can't discover an answer to something, instead it needs to be demonstrated that it is beyond us. 4. This is a little bit more difficult because absolute proof would require that we can use our own epistemic apparatus to justify itself. This is circular. In other words how can you know that you are not mistaken about something? If you were mistaken, you wouldn't think you were. So such arguments are fruitless. Proof is proportionate and subjective.
Regarding the question itself: Essentially natural laws are discoverable as intellectually abstract principles. That is the premise of the question. These generalized norms exist regularly as particulars in the mind, but do not ever exist as any particular in the material world and only exist in the world at all as instantiations of the generalized norms. Therefore, it seems that the reason that the natural laws are discoverable by the intellect is that they are the sort of thing which belongs to an intellect. In other words, they are the product of or literally the activity of a mind. That mind is God.