Economists' ignorance of how the economy works

Which one factor—(a) economists' ignorance of how the economy works, (b) shorter time lags between policy implementation and the response of economic agents to policy changes, (c) inaccurate and incomplete statistics, (d) pressure from private lobbyists for government favors, or (e) the president's desire to get reelected—would likely assist the federal government in achieving macroeconomic stability? Explain your answer.