Which of the following yields more than twice the energy compared to carbohydrates?

Following are the statements with reference to 'lipids'.
$(a)$ Lipids having only single bonds are called unsaturated fatty acids.
$(b)$ Lecithin is a phospholipid.
$(c)$ Trihydroxy propane is glycerol.
$(d)$ Palmitic acid has $20$ carbon atoms including carboxyl carbon.
$(e)$ Arachidonic acid has $16$ carbon atoms.
Choose the correct answer from the options given below.

The component with the highest energy content is ...

Sex hormone is a

$A$: Linolenic acid is an essential fatty acid.
$R$: Linolenic acid cannot be synthesized in human beings.

Lipids can be $......$.