How would one take advantage of this arbitrage opportunity?
Hi: Don't think of a specific case. Just think of investment A and investment B and assume that the return on both investments is the same. Also, assume that investment A costs more to invest in than investment B. In that case, you would sell some amount, X, of investment A to Mr. Pushover and buy the same amount, X, of  investment B with the proceeds from Mr. Pushover ( and you'll have a little left over since A costs more than B. Call  what's left, L, for leftover ).

Then, when the investment horizon is complete, you pay Mr. Pushover the return with the return that you made from investing in B.

But,  now you still have L left so you made L with no risk. That's the arbitrage. I hope that helps. To summarize, if two investments return the same thing, they have to cost the same thing or else there's an arbitrage.