$17.$ What is the primary characteristic of petrochemical products?

a$)$ Biodegradable

b$)$ Renewable

c$)$ Derived from renewable resources

d$)$ Derived from fossil fuels

$18.$ Which of the following is a common application of ethylene?

a$)$ Production of pharmaceuticals

b$)$ Manufacturing of fertilizers

c$)$ Production of synthetic rubber

d$)$ None of the above