Thanks for the specificity of your analysis! Because there is a lot going on in your question, I will go line by line in my response:
Upon reviewing, I can see why E gives an alternative factor, as well as effect without the cause (drop in crime rate without the major policy changes in place yet).
(E) does give an alternate cause, the hiring of more police officers, but this is not an example of "effect without the cause." The stimulus does not say there was a drop in the violent crime rate before the mandatory sentencing law was enacted, and you can't assume there was. The stimulus gives up no information about whether violent crime increased, decreased, or stayed the same in the year before the mandatory sentencing law was enacted.
Your next question refers to the numbers and percents in the stimulus:
However, I am struggling to understand why it is correct that the stim talks about crime rate in % and answer E is comparing something in number (#), new police offers each year. I thought when the stim is talking about % we need another answer that matches with the stim (%). Thats why I got rid of E because of the mismatch.
The flaw in your reasoning is that you are generalizing a little too much about Powerscore's number/percentage tips. The tip is that if you are only told a raw #, you do not know anything about a %, and if you are only told a %, you don't know anything about a number. So you can't simply see a % in the stimulus and a # in the answer choice and eliminate the answer based on that. The other inaccuracy in your statement is that the tip about %s and #s applies when you are talking about the same quantity. For example, knowing the percentage of women in a law school class does not tell you the number of women in the same class. You would have to know the total number of students in the class to determine the % from the # or vice-versa. But in this problem, the % is about violent crimes (crime rate means # of crimes divided by # of people). But the # is the number of police officers hired. It's apples and oranges.
Your last question is about the shift in language from "violent crime rate" to "crime rate":
Also, the conclusion talks about "crime rate" in general whereas, the stim talks about "violent crime rate." So is the conclusion saying because there is an increase in violent crime rate and put in prison there is a decrease in crime rate in general? Or the conclusion is equating crime rate = violent crime rate as being the same thing?
Let's look closely, though. The conclusion says "the
drop in the crime rate," which refers to the drop previously mentioned, the drop in the violent crime rate.
Compare to this example: Yesterday I saw a black cat. The
I am less specific in my second sentence, but it is clear I am referring to the black cat because I didn't mention any others.
I hope this helped. Great questions!