Journalist: In 2005, the current mayor of Plainfield was elected. Each year since then, about 300 violent crimes have occurred in Plainfield. In 2000, only about 100 violent crimes were committed. So the new mayor’s administration was less effective at controlling crime than the old administration was.

Mayor’s Representative: But one reason the mayor was elected in 2005 is that the population of Plainfield increased by 300% between 2000 and 2005, and many of the new residents of Plainfield voted the mayor into office.

The mayor’s representative challenges the journalist’s argument by doing which of the following?

A- Presenting data that extend further than the journalist’s data

B- Introducing evidence that undermines an assumption of the journalist’s argument

C- Questioning the accuracy of the evidence presented in support of the journalist’s conclusion

D- Pointing out that the argument illegitimately draws a general conclusion on the basis of a sample that is too small

E- Stating that the argument treats information about some member of a group as if it applied to all members of the group

The journalist concludes by saying that efficacy of current mayor in controlling crime is less compare to the previous administration. Implicitly it is stated that since he is not able to control crime he might be put off the chair or people may not vote him again.
Now this is an assumption.
What Mayor's representative is telling that there was all together a new reason and that was the population increased by 300% and most of the newcomers voted for him.So he is trying to break the link between controlling crime and coming which was assumed by the journalist.
Option B reflects that.
Thank you!

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Hi

The Assumption in Journalist's argument is Total population remains same from 2000 to till date. Because he is making a conclusion on the basis of absolute nos.

Mayor's representative weakens Journalist's argument by showing that Total population was quadrapled.

Say, In 2000, Population size = 1000 , No of crimes = 100. ( Crime per capita = 10 %)
In 2018, Population size = 4000 , No of crimes = 300. ( Crime per capita is less than 10 %).
Administration is more effective than thought by Journalist.
So argument is weakened.
Only B fits.