According to the market segmentation theory of the term structure of interest rates

a$.$ The slope of the yield curve becomes flatter as the supply of securities increases in the short$-$term market and

increases in the long$-$term market

b$.$ The slope of the yield curve becomes flatter as the supply of securities decreases in the short$-$term market and

decreases in the long$-$term market

c$.$ Investors are indifferent between securities of different maturities

d$.$ The preference for particular maturities can affect the prices and yields of securities with different maturities and

therefore the shape of the yield curve