use of apostrophe in parallelism apart from list

[AvinashR698]

Many employees in the energy sector must choose between jobs offering substantially higher pay, but requiring long hours, physically taxing labor, or relocation to remote, sparsely populated areas, and less physically intense, but lower-paying, jobs in larger metropolitan areas.

In the following sentence

As i understood from Sentence correction book -
1. ,FANBOYS conjunction is used to connect two independent clauses
2. ,and for list of three or more items.

But, in the above sentence i could find ,and and ,but used to connect - , and less physically intense, but lower-paying, jobs which are not Independent Clause.

Please help me to understand this concept.

Thanks

[RonPurewal]

hi,
as per the forum rules, you must cite the original source of the problem, and reproduce the problem EXACTLY as originally provided (including ALL answer choices, and indicating which choice is the officially correct answer).

original source = the company that holds the copyright (i.e., not another forum or other secondhand source). without such a citation, we can't discuss the problem here.

thank you.