The disadvantage of the four-model approach is

It is the added time and cost that is needed to develop a logical and physical model of the current system. 

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.

Any answer choices that would me answer your question?