原始口腔的组成是（）

A.额鼻突、上颌突、下颌突

B.额鼻突、侧鼻突、下颌突

C.中鼻突、侧鼻突、下颌突

D.额鼻突、球状突、下颌突

E.球上突、侧鼻突、下颌突

An analyst does research about required rate of return. With respect to an investor's required rate of return, those components included in the nominal riskfree rate of return will most likely:

A. affect all of the investments.
B. be relatively constant over time.
C. affect the yield spread between government securities and corporate securities.