Which choice is best? A. The job offered full medical benefits, but I already had them from my wife's job. B. The job offered full medical benefits; but I already had them from my wife's job. C. The job offered full medical benefits I already had them from my wife's job. D. The job offered full medical benefits but I already had them from my wife's job.

The correct answer is letter "A": The job offered full medical benefits, but I already had them from my wife's job.

Explanation:

Commas are used in different situations such as: to separate a series of words, to connect two independent clauses, to set off introductory words or phrases, to avoid confusion, to separate quoted segments, to set off expressions that interrupt the sentence flow, and to separate dates, years, and addresses.

In the example:

The job offered full medical benefits, but I already had them from my wife's job.

The comma separates two independent clauses which are those that convey meaning by themselves.