Previous economists such as John Maynard Keynes and Milton Friedman believed it was important to monitor and control economic fluctuations. Which statement about modern macroeconomists is true?

Modern macroeconomists believe that the business cycle model is no longer valid for today's complex economy.

B.
Modern macroeconomists continue to study the business cycle in an attempt to prevent recessions and make the economy more stable.

C.
Modern macroeconomists have mastered the complexities of the business cycle and can now prevent recessions in the national economy.

D.
Modern macroeconomists agree that the business cycle is impossible to regulate and are seeking better methods of preventing recessions.