Final answer:
The adjusting entry that Starr Corporation should make on December 31, 2020 is to debit Interest Receivable and credit Interest Revenue, $12,000.
Step-by-step explanation:
The adjusting entry that Starr Corporation should make on December 31, 2020 is option a. Debit Interest Receivable and credit Interest Revenue, $12,000.
Since the note has a face value of $600,000 and an 8% interest rate for 3 months, the interest for one month would be $4,000 ($600,000 * 8% / 12 months). Since December has one month remaining in the 3-month period, the adjusting entry would be $12,000 ($4,000 * 3 months).