Lucien: Public-housing advocates claim that the many homeless people in this city are proof that there is insufficient housing available to them and ttherefore that more low-income apartments are needed. But that conclusion is absurd. Many apartments in my own building remain unrented and my professional colleagues report similar vacancies where they live. Since apartments clearly are available, homelessness is not a housing problem. Homelessness can, ttherefore, only be caused by people' s inability or unwillingness to work to pay the rent. Maria: On the contrary, all recent studies show that a significant percentage of this city' s homeless people hold regular jobs. These are people who lack neither will nor ability. Lucien's argument against the public-housing advocates' position is most vulnerable to which one of the following criticisms? ["It fails to address the issue, raised by the public-housing advocates' argument, of who would pay for the construction of more low-income housing.", 'It overlooks the possibility that not all apartment buildings have vacant apartments for rent.', "It offers no justification for dismissing as absurd the housing advocates' claim that there are many homeless people in the city.", 'It responds to a claim in which "available" is used in the sense of"affordable" by using "available" in the sense of "not occupied. "']