Understanding the argument -
Ten years ago, the country of Vorland adopted new automobile safety regulations requiring airbags and better seat belts in all new automobiles. Fact
Since then, the annual number of drivers and passengers hospitalized overnight or longer for injuries sustained in automobile accidents has steadily declined. Fact
Clearly, the regulations have made Vorland's automobiles safer for drivers and passengers who are involved in accidents. - Conclusion. Two independent events, and we convert them to a causal connection. So earlier, there were 1000 automobile accidents, out of which 100 passengers were HOSPITALISED for automobile accidents (the rest 900 were, say, minor or didn't require hospitalization). And now, after the introduction of regulation, the "number of drivers and passengers HOSPITALISED overnight or longer for injuries sustained in automobile accidents has steadily declined," say to 20.
If it helps, let's look at it this way: the regulations have made Vorland's automobiles safer for drivers and passengers involved in accidents BECAUSE
1. The annual number of drivers and passengers hospitalized overnight or longer for injuries sustained in automobile accidents has steadily declined
2. Ten years ago, the country of Vorland adopted new automobile safety regulations requiring airbags and better seat belts in all new automobiles
What can weaken the conclusion - what if the "1000" number has come down to 80? So, the number of drivers and passengers HOSPITALIZED will also reduce. If that happens, it means there is some alternate cause Z (which we do not know what) that caused the number of drivers and passengers HOSPITALIZED to reduce.
So, we need to guard the conclusion against this weakness. How? By assuming that this didn't happen.
Option Elimination -
(A) The citizens of Vorland generally obey all national and local speed limits. - Applicable when the number of accidents was higher as well. Distortion.
(B) Of the patients treated at hospitals in Vorland, the percentage of being treated for injuries sustained in automobile accidents has decreased in the past ten years. - This is a classic trap. The conclusion talks about numbers, and the answer choice talks about percentages. Percentages can be misleading. Say earlier, out of 1000, 100 were HOSPITALISED, showing the percentage to be 10%. Suppose the total number of automobile accidents is 10,000, and now the number of drivers and passengers HOSPITALISED is 500, showing the percentage as 5%. But has the number of HOSPITALIZAIONS reduced as well? No. The number has increased five times. Distortion.
(C) The safety improvements required by the regulations have not significantly affect the price of new automobiles. - Had we been given the argument that buyers are price-conscious, we would have considered this a contender. But since we don't know about that, this is out of scope. What if Volland is one of the wealthiest countries in the world, and people don't care about price? Or it can be the poorest. We don't know, so let's not make any unnecessary assumptions to make it work.
. More importantly, the argument does not talk about the price consciousness of automobile buyers.
(D) There has been no increase in speed limits on Vorland's major highways over the past ten years. - Distortion.
(E) Over the past ten years, there has not been a steady decline in the annual number of drivers and passengers involved in automobile accidents in Vorland. - Please read the question stem clearly. It is that the number of drivers and passengers HOSPITALISED has reduced out of the total number of drivers and passengers involved in automobile accidents. But if somehow we didn't read well and subconsciously assumed that the number of drivers and passengers HOSPITALISED has reduced out of the total number of accidents (Auto or non-auto), then this option may sound as if we already know it from the passage and doesn't add value and we may strike it off. But "read question stem" carefully. Correlate each line with the past one to make sense.