Why is the answer "C"?

The main conclusion of the argument is: "further government spending to provide low income housing is not the cure for homelessness." Why? Because despite the fact that homelessness is a serious problem, even a cursory glance at the real estate section of any major newspaper, which will show that there is no lack of housing units that are available to rent. So, we can make the intermediary conclusion that the frequent claim that people are homeless because of a lack of available housing is wrong, which leads us to conclude out main point (see above). So, we are asked to determine how the statement "homelessness is a serious social problem" figures in the argument. Answer choice (A) states: "it suggests an alternative perspective to the one adopted in the argument." The argument is not disagreeing that homelessness is a serious social problem. The argument is saying DESPITE THE FACT that homelessness is a serious social problem, it will not be fixed by further spending on low income housing. Thus, this statement is not an alternative perspective, which the argument has not adopted. For this reason, answer choice (A) is not correct. Hope that clears things up! Please let us know if you have any other questions.