Which of the following correctly explains how expansionary monetary policy works?
a.G↑ ⇒C↑ ⇒Y↑
b.M↑ ⇒i↓ ⇒I↓ ⇒ Y↑
c.M↑ ⇒ ⇒1↑ ⇒Y↑
d.T↑ ⇒ C↑ ⇒ Y↑