Look at the formula ROE = ROA*EM, and think of two ways to increase ROE. Which is easier?

A: Increasing EM is easier, since it can be done by simply issuing more equity.

B:Increasing EM is easier, since it can be done by simply granting more loans or buying back shares.

C:Increasing ROA is easier, since it can be done by simply choosing higher return assets with the same risk profile.

D:Increasing ROA is easier, since it can be done by simply raising the interest rates on loans

Please give me the answer with explanation as well. Thank you!