Certain instruments used in veterinary surgery can be made either of

Official LSAT Test Prep 9, Section 2, Q-17
(B) If this one reminded you of a logic game, so much the better: Your LG skills serve
you well here. First, note that the question asks for the one thing that cannot be true. Next,
draw out the information the stimulus gives — and doesn’t give. There are two sets of
instruments; the same procedures are done to each; and the procedures yield similar
results. It takes more energy to sterilize a set of these instruments than it does to
manufacture them. But we don’t know how many instruments make up each set, nor do
we know exactly how much energy it takes to manufacture either set. It could take more to
make nylon tools, or it could take more to make stainless steel, or it could take equal
amounts of energy for both. We just don’t know. Unfortunately there’s no way to predict
the answer here. It’s just a matter of slogging through the choices until you find the right
one.
(A) could be true. If the same amount of energy was required to manufacture both the
nylon and the steel instruments, then sterilizing the nylon instruments would have been
more energy consuming than sterilizing the steel. (B), however, can’t be true, and yes, it
takes a little math-thinking, but that’s life. (You could have skipped this choice and
checked out the others; if all of them can be true, then (B) must be correct whether or not
you understand why.) If 50 complete sterilizations of the nylon instruments took 3.4 times
the energy to make that set, then they should be able to do roughly 15 sterilizations with
the same energy as manufacture. One complete sterilization, then, must have taken far less
than the energy of manufacture. (C) could be true; as we noted above, we don’t know how
many types of instrument appear in each kit, so there could be more nylon instruments
than steel. Since both kits were sterilized an equal number of times, more nylon
instruments could have been sterilized. (D) absolutely could be true, since we don’t know
how much energy was required to produce either set. (E) is also quite possible. If
materials are cheap, and energy is very expensive, then using far more energy to sterilize
than manufacture steel instruments could make sterilizing them more expensive than
making them in the first place.