Consider the body of economic research regarding the impact of immigration on the wages earned by natives. One approach is to link empirically changes in immigrant flows to changes in wage differentials across regional labour markets. What of the following is true about that approach?

A: It is a lot like the natural experiment approach - such as the approach utilized in the Mariel boatlift study

B: Counterfactual situations of the absence of immigration can be observed in this case.

C: It is similar to the approach used to examine the process of assimilation

D: Wages might be relatively high in cities that draw immigrants, thus confounding any estimation of that impact

E: It has become accepted as the best approach for addressing this issue.