I think its D..here is why

The conslusion: "80 percent were not wearing seat belts at the time of their accidents"

this will not be true unless D is true which says

"More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents. "

Mathematically, D supports the conclusion..

Hope this helps..

IMO its A.

and here is my twisted (hopefully correct) logic...

According to the argument, 20% of people sustained "severe injuries" despite wearing seatbelts. Despite this fact, the argument concludes that wearing seat-belts reduces the risk.

Also, the argument does not explitcitly state if there are pasengers that were not severly injured.

Choice (A) says that in all survey, there were MORE THAN 20% of people wearing seatbelts, which means there were those that were not severly injured and more importantly, they wore seatbelts, thus strengthening the argument!

sankruth, can u pls explain it more clearly? I am not getting it actually. Yop! The OA is A itself. Guys some more input with explanation - I think - needed here...

camitava wrote:sankruth, can u pls explain it more clearly? I am not getting it actually. Yop! The OA is A itself. Guys some more input with explanation - I think - needed here...

Amitava,
I will do my best here...

If you read carefully, the survey included people who had accidents. Thus there could be two categories:
SI - Severely injured and
NSI - not severely injured

However all statistical data is about SI. None about SI

Lets assume there were 100 people who were SI. 80 did not wear a seat-belt, which means 20 wore a seat belt and still got SI. Based on this fact it would be incorrect to conclude that wearing seat-belt reduces the risk of SI.

A states that there were more than 20% who wore seatbelts which includes the 20% that had SI and the rest NSI (the crucial bit) - which was not clear from the argument. So A strengethens the argument by showing there were some people who did not get severely injured because they were wearing seatbelt.

Yes, you can argue that it does not say how many people who had NSI wore seatbelts and for all you know it could be just 1% while 20% sustained SI despite wearing seatbelts. But if you revisit the other options after using this analogy you will find that they do not even go as far as A towards strengethening the argument. Very tricky question indeed! Definetely not at 1m 50sec one!

Thanks a lot, sankruth... Now I have understood.

i feel it's A