Now it's easy enough to find the answer; Hoffman elimination isn't going to happen from the methyl, and the n-propyl doesn't have $\beta$-hydrogens as acidic as that of the ethyl. It doesn't feel like the hydrogens in the ring are more acidic, either, so the product involves ethene. Simple enough.
But this lacks rigor. How do I actually evaluate the inductive effect on the $\beta$-carbons on the ring? If I have to compare it to some other fragment less obvious to win than ethyl, where do I start counting the carbons that inductively push electron density onto the $\beta$-carbons on the ring?