Councilperson X has stated that they have an obligation to help ensure that electricity rates are the lowest possible. We are told that the proposed design for a new generating station would allow for the lowest rates. And for this reason Councilperson X believes that this design must be the design they endorse if they have no choice but to approve construction of a new plant.
Councilperson Y states that helping to ensure the lowest electricity rates is not the council's only job. Councilperson Y explains that they also have an obligation not to lower the quality of life of their community; and a plant of such design would damage their community's air quality to such an extent that the benefit of lower rates would be outweighed. Therefore, Councilperson Y is advocating against the design.
So, the two councilmen are not disagreeing over whether the building of a new generating station should be the case, i.e. answer choice (A). They disagree over endorsing a plant of the type specified by the design in question, if they are to build a new generating station, i.e. answer choice (D).
Councilperson X never gives an opinion on whether a new plant should be built. She merely states that if a new one is to be built, then we should endorse the proposed design. Councilperson Y, likewise, never mentions whether a new plant should be built. She merely explains that endorsing the proposed design would be ill-advised.
Hope that clears things up! Please let us know if you have any other questions.
