Politicians sometimes use focus groups to help them arrive at popular

I read the posts for this topic, but I am not convinced how option B is better than A.
Politician is using focus group to arrive at a position, means he is using their thoughts or views to help himslef arrive at a conclusion.
So if they themselves are not aware about the topic how will it help politician to conclude anything about a policy.
Please explain.

Here is the OE

Analysis
To answer this question, you must first find its conclusion, premise, and assumption. Here are the conclusion and premise:
Premise: The politician bases his or her opinion on the consensus opinion of the focus group.
Conclusion: A focus group can help a politician arrive at a popular policy position.
This argument relies on a key assumption. The necessary link is that the consensus opinion of the focus group is going to be a popular policy position. So, to evaluate this argument, it would be useful to have some information to that effect. Choice A does not address this issue. Even if you knew whether the members of the group were well informed about the policy, you wouldn’t know whether it would result in a popular policy position. Choice B addresses the assumption. If the consensus group was a representative sample of voters, then it is more likely that the conclusion is true. But, if the group was not representative, you would be less likely to accept the conclusion. Choice C is out of scope because it doesn’t matter if the politician agrees—it just matters if the position is a popular one. Choice D might have some value if you assume that the group members’ knowledge might affect their opinions, but that reasoning is going too far beyond what the choice actually states. Choice E is also out of scope because the point of the focus group is to find a popular opinion for the politician to support; the group’s feelings about the politician are inconsequential.

Hope it Helps

Politicians sometimes use focus groups to help them arrive at popular policy positions. A staffer will assemble a group of citizens and ask the members of the group about their feelings on a particular issue. The politician will then base his or her position on the consensus opinion of the focus group.

The answer to which of the following questions would be most useful in evaluating the value of focus groups to a politician?

A. Are the members of the focus group well informed about the policy issues in question?
Not relevant,the focus group is given project to complete the servey based on limited questions /feedbackss and the knowledge of the members is irrelevant.

B. Are the members of the focus group a representative sample of the voters in the politician’s district?
Correct choice,Only if the members are true representation of the voters in the politicians district the servey would be a success,other wise ther is not use of the survey at the first place.

C. Does the politician agree with the policy position supported by the focus group?
the opinion of the politician is not relevant.

D. Does the focus group know that its responses are being used to help a politician develop a policy position?
not relevant.

E. Does the focus group support the politician that is relying on its opinions?
Not relevant.