Okay, you've got a "K Triple", and what you want to do is start with the middle one to determine which one of these would be an effective K triple. Start with the middle value of K, and immediately look and see to the left which number or value would be half of K. Well, that immediately narrows it to C and D as your only two possible answer choices; and you look to the right and see which number represents 3/2, or 1 1/2 times K. That takes you to C, because D, 1000, is twice 500, but 75 is 1 1/2 times 50