The most important thing interest groups need to be effective is

The answer is: Access to politicians. 

It is probably Access to politicians.

This question is an opinionated one, and we don’t know anything about the module or anything, thus we can not answer it. but if you are having trouble on what it is asking basically it is just asking to (using your knowledge on the topic) say which topics you were most interested and which were the most challenging.hope this : p