If Matter Is Atomic, Then We Can Observe Only Modes $\lor$

If matter is atomic, then we can observe only modes. If we do not know of the world by pure reason, then, again, we can observe only modes. Either matter is atomic or we do not know of the world by pure reason. So, we can observe only modes.
-Which of the following propositions is an immediate (one-step) consequence in PL of the given premises?

A) A $\lor$ M
B) ∼R $\lor$ M
C) A ⊃ ∼R
D) M $\lor$ M
E) None of the above