confusing CR

[shilpishrestha]

The United States will soon begin spot checking all shipments of imported coffee for tainting by sandfly larvae. Any coffee found to be so tainted will be destroyed. Officials predict that the spot checks will result in the destruction of approximately 10 percent of all coffee imported into this country. Even So, However, the checks will miss about half of the tainted coffee sent here, since it is estimated that 20 percent of all the cofee worldwide is tainted by sandfly larvae.

The author of all hte passage above is neccessirily assuming which of the following?

a. spot inspections will not succeed in preventing unacceptable amounts of tainted coffee from entering the country.
b. inspectors can detect sandfly larvae in only half of the tainted shipments they inspect.
c. the proportion of imported coffee tainted by sandfly larvae is representative of the proportion of coffee so tainted worldwide.
d. spot checking will mean that only 10 percent of all imported coffee will be inspected for tainting by sandfly larvae.
e. the 80 percent of imported coffee shipments that are not tainted by sandfly larvae should not be inspected.

[NishantG]

Imo C

[bolt_n_blue]

yep.. IMO C as well..!

[Lhomme]

shilpishrestha,
C looks correct.

Did you have a doubt about any other answer option ?

[shilpishrestha]

Yes... I haven't understood y C is the answer.... Please explain.
BTW Official Answer is C.

[bolt_n_blue]

The argument says..

evidence:
"20 percent of all the cofee worldwide is tainted by sandfly larvae."

conclusion is instead based on
"Officials predict that the spot checks will result in the destruction of approximately 10 percent of all coffee imported into this country. Even So, However, the checks will miss about half of the tainted coffee sent here"
i.e imports in US too are tainted..

see a scope shift.. on 1 hand world imports and on the other.. US imports..

so the assumption that will justify this scope shift is C