一道句子完成题

lsat 14/1/question 9

9. In a mature tourist market such as Bellaria there are only two ways hotel owners can increase profits: by building more rooms or by improving what is already there. Rigid land-use laws in Bellaria rule out construction of new hotels or, indeed, any expansion of hotel capacity. It follows that hotel owners cannot increase their profits in Bellaria since Bellarian hotels _____.

Which one of the following logically completes the argument?

(A) are already operating at an occupancy rate approaching 100 percent year-round

(B) could not have been sited any more attractively than they are even in the absence of land-use laws

(C) have to contend with upward pressures on the cost of labor which stem from an incipient shortage of trained personnel

(D) already provide a level of luxury that is at the limits of what even wealthy patrons are prepared to pay for

(E) have shifted from serving mainly Bellarian tourists to serving foreign tourists traveling in organized tour groups

------------------The answer is D. But why???
这类题该怎么做呢，我怎么觉得没有思路呀？