High-density polyethylene is composed of:
a) a mixture of polyethylene and polystyrene.
b) primarily linear, unbranched chains of polyethylene in a close packing arrangement.
c) polyethylene with high density plasticizers added to increase density.
d) primarily highly branched, non-linear chains of polyethylene in a diffuse packing arrangement.

c. ) polyethylene with high density plasticizers added to increase density.

Explanation:

High - density polyethylene -

Polyethylene is a crystalline structure , which have a very wide area of application , it is a type of thermoplastic polymer .

It is produced in huge tons every year due to its wide range of application.

Commercially it is produced by the very famous , the Ziegler - Natta catalysts .

In the polyethylene , a high - density polyethylene is added in order increase its density , and hence this type of polyethylene is referred to as high - density polyethylene .