Hi jasourne,

B is a much better answer than C because B is easier to support; it must be true. We know from the prompt that if these systems are adjusted to be more forgiving (to widen the range of inputs that will be considered valid), the likelihood of admitting impostors will go up. This is just another way of saying what's in answer B: if we make the system less forgiving (a very narrow range of inputs will be considered valid) in order to keep out impostors, it will sometimes keep out legitimate access-seekers (because two fingerprints can never really be identical for example).

B is a correct inference/conclusion because it can be supported without the need for any new assumption.

In answer C, the phrase "appropriate ONLY in situations..." should have raised a flag. Extreme language (only, always, never...) is typically impossible to prove with the few premises available in CR arguments. Specifically, while answer C claims that the biometric system should be used only where admittance of impostors is not a big problem, we know from the premises that this is not necessarily the case: these systems can be used where admittance of impostors is a problem because the system can be adjusted to validate a more narrow range of inputs. This will keep out more impostors (but the downside as highlighted by the passage is that it will also keep out some legitimate access seekers)

Take-Away: when drawing inferences/conclusions, pick the answer choice that you can prove from the premises alone (without requiring additional assumptions) and avoid answers that are strongly worded (always, never, only) unless you can prove them.

-Patrick

as the passage employs a very flexible language with words like rarely and minimise

extremeties can be eliminated..

now i get it ..

thjis is cr question anyway ..
you should have posted it there for better response and replies from the members