According to the market segmentation theory of the term structure,

Question $9$Answer

a$.$

bonds are inherently marketable

b$.$

bonds of one maturity are perfect substitutes for bonds of other maturities; therefore, interest rates on bonds of different maturities do not move together over time.

c$.$

the interest rate for bonds of one maturity is determined by the supply and demand for bonds of that maturity.

d$.$

investors' strong preference for short$-$term relative to long$-$term bonds explain why yield curves typically slope downward