CR Question

read choice e carefully: it says 'if parts are made for cars manufactured in our country, ...' that is a very sweeping generalization; it covers all parts ever made for our cars, no matter where or how they're made. taken literally,** this statement would even extend to parts made by six-year-olds from the ruins of cardboard boxes.

the argument, by contrast, is strictly limited to parts made by Clark.

see below for one possible explanation of why you may have chosen choice e.

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the only evidence the argument gives for the superiority of Clark parts is their having passed government tests. based on that evidence alone, the argument recommends choosing the Clark parts over 'cheap look-alikes that are poorly constructed...'.

that recommendation REQUIRES the assumption that, if parts pass the government tests, they must be better than the cheap lookalikes.

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ONE REASON YOU MAY HAVE CHOSEN E:
you may have misread or misinterpreted the prompt question.

if the prompt question were:
'which of the following, if true, would support the argument?'
then choice e would be correct. however, choice e is not a REQUIRED ASSUMPTION (which is what this problem asks for), and is indeed unrealistic for the reasons mentioned above.

read the problem carefully!