The Government of Country a Decided to Introduce a New

The government of Country A decided to introduce a new treatment strategy for disease X.It was decided that,starting in January 1,2019,all patients diagnosed with disease X in public hospitals would receive the new treatment.Researchers were asked to evaluate the new treatment.Which of the following designs is the best approach to evaluate the new treatment?

A) Randomized clinical trial
B) Case-control study
C) Cross-sectional survey
D) Before-after study
E) Case-series