What is inertia? What is unbalanced force?

inertia is a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

An unbalanced force is an unopposed force that causes a change in motion

gatsby's clothes have a symbolic meaning, as the use of colour and fabric in his clothing demonstrates his hope, dreams, and wealth. gatsby's clothing symbolizes his wealth through his torn shirt, his silver and gold suit, and his english shirts.

his occupation are

businessman yachtsman soldier entrepreneur bootlegger

i believe it is the first choice (1.)

because the major theme is(“both the wild and civilization have rules.”)

and also as u said,( based on what buck learns within the call of the wild, "both the wild and civilization have rules".this is true of humans within society as well.