pratyushakosaraju
D sounds like a premise. An assumption cannot be a premise. Assumption should be a link between premise and conclusion.
Let me give it a try:
Even though only 5 percent of people living in Hutorsville own guns, the Hutorsville Police Department reported that 25 percent of those arrested for robberies in Hutorsville had guns. Clearly, a person who has a gun is more likely to commit robbery regularly than a person who does not have a gun.
Lets create a scenario:
In a town of population 100, 5 person own guns. Tom, Dick, Harry, John, and Jeff.
Lets say 4 robbers arrested, one of them was Tom and others were from rest of the population M1, M2,M3.
Above scenario satisfies the 25% fact.
But conclusion says : a person who has a gun is more likely to commit robbery regularly than a person who does not have a gun.
Thus we can discard above mentioned scenario... bcz author assumes involvement of a person who has gun in different robberies.
Another Scenario:
Lets say 100 robberies committed, in 25 robberies Tom, Dick, Harry, John, and Jeff were arrested. 5 robberies committed by each of them.
Lets us analyze option B and D.
(B)People who were arrested for robbery were more likely to commit robberies regularly than people who were not arrested.
We can not tell about non gun holders whether they were also involve in regular crime... may be M1,M2,M3...M75 arrested only once in 75 arrests.
But we can surely say that gun holders regularly committed robbery and were arrested in 25 cases.
(D)Many people who were arrested for robbery have been arrested before.
Now again it is supporting the conclusion that gun holders regularly committed crime.. also option D is not stated in argument under any premise.
"Even though only 5 percent of people living in Hutorsville own guns, the Hutorsville Police Department reported that 25 percent of those arrested for robberies in Hutorsville had guns."
In this question option D and B both are supporting the conclusion.
Further if you refer the similar OG problem on vehicles equipped with radar, you should be able to see the difference in choice B and D.
Choice B is talking about drivers, and choice D is talking about vehicles.