This is a weaken question. Let's briefly look at the argument:
Pr: Cars built smaller after 1977 to make them more fuel-efficient have a higher rate of accident-related fatalities compared to older larger cars. C: For this reason, we oppose guidelines that would require us to produce cars with higher fuel efficiency.
This is quite a logical leap and requires several implicit assumptions:
(1) no alternative reason could explain higher accident fatalities after 1977, e.g. more traffic overall, higher speed limits etc; (2) higher fuel efficiency requires making cars even smaller; (3) no other technological advances could counter the negative effects of making cars more fuel-efficient in terms of safety
Let's look at (C). (C) demonstrates that our assumption (2) above is false - it is possible to make LARGE cars more fuel-efficient using new technology. Since the executive cites the smaller size as the primary cause of higher fatalities, his argument no longer makes sense if it is possible to meet fuel standards without compromising on vehicle size.