Isomerization of Hydrocarbons Is Important in the Refining of Petroleum

Isomerization of hydrocarbons is important in the refining of petroleum. A simple example is that of butane, which has only two isomers: Which of the following statements is most correct?

A) At standard temperatures, n-butane is the preferred isomer.
B) At temperatures less than 450, n-butane is the preferred isomer.
C) At temperatures greater than 450ºK, n-butane is the preferred isomer.
D) At ambient temperatures, a sample of n-butane and isobutene which was at equilibrium would contain barely any butane.
E) A 1:1 mixture of butane and isobutane is at equilibrium at room temperature.