The Bigbook's Hard Quant Question

I solved Q26 of Test 1 Section 3 from the Big Book but didn’t end up with Answer choice “C”. Did anybody figure out why answer choice is just C but not B and C? Choice B and C both fulfills the question. I would like to find out where I went wrong if Answer key is correct. Thanks!!

Let s = -2 and t = -2. What happens?

Then multiplication of st won’t be smaller than 1.

Which fails the condition given in the question for option B. It does say “can”, but can you use the above example I gave to more generally show that option B cannot be true?

what happens if s=0.5 and t=-4? How is option C correct then?

Is it implied from the question statement already that s and t have to have the same signs? That would make the numbers assumed by me incorrect. @Leaderboard

The keyword here is can. This means that it needs to be true only in one case, and crucially does not need to work in every case.

In option B, you can show that it never works.

After putting emphasis on “Can” and choosing specific example s= -0.999 and t= -1.0001, we get st = 0.9990. That would satisfy the answer choice C. I do see why answer choice can’t be B. Thanks you all for your input!