Waxes do not contain glycerol in their structure,but instead contain which type of alcohol?

Read the following statements on lipids and find out the correct set of statements:
$(a)$ Lecithin found in the plasma membrane is a glycolipid.
$(b)$ Saturated fatty acids possess one or more $C=C$ bonds.
$(c)$ Gingely oil has a lower melting point,hence remains as oil in winter.
$(d)$ Lipids are generally insoluble in water but soluble in some organic solvents.
$(e)$ When fatty acid is esterified with glycerol,monoglycerides are formed.
Choose the correct answer from the options given below:

Which groups are present in the structures of sterol and sterone,respectively?

Which of the following elements is absent in the structure of lecithin?

Which type of lipid does not contain any fatty acids?

Which of the following groups is present in sterols?