$36.$ In the context of oil reserves, what does "proven reserves" mean?

A$)$ The total quantity of oil in the ground

B$)$ The amount of oil that is technically recoverable

C$)$ The volume of oil that can be economically recovered

D$)$ The oil quantities being currently extracted

$37.$ The process of converting unsaturated hydrocarbons into saturated hydrocarbons is known as:

A$)$ Cracking

B$)$ Isomerization

C$)$ Hydrogenation

D$)$ Reforming

$38.$ What characteristic of lubricants is measured by its viscosity index?

A$)$ Resistance to freezing

B$)$ Resistance to oxidation

C$)$ Change in viscosity with temperature

D$)$ Ability to reduce friction

$39.$ Which of the following is not a primary component of natural gas?

A$)$ Methane

B$)$ Ethane

C$)$ Propane

D$)$ Benzene