A Change in Which of the Following Parameters Shifts the AD

Multiple Choice

A change in which of the following parameters shifts the AD curve $\tilde { Y } _ { t } = \bar { a } - \bar { b } \bar { m } \left( \pi _ { t } - \bar { \pi } \right)$ ?

A) $\pi _ { t }$
B) $\bar { a }$
C) $\bar { b }$
D) $\bar { m }$
E) None of these answers are correct.