On Oct 1, 2019, a Firm Purchased a 1-Year Insurance

On Oct 1, 2019, a firm purchased a 1-year insurance policy for $2,400 and paid the full premium in advance. The adjustment needed on December 31, 2019, to report the amount of insurance that had expired, would be:

A) a debit to Insurance Expense for $1,800 and a credit to Prepaid Insurance for $1,800.
B) a debit to Insurance Expense for $2,400 and a credit to Cash for $2,400.
C) a debit to Insurance Expense for $600 and a credit to Prepaid Insurance for $600.
D) a debit to Prepaid Insurance for $600 and a credit to Insurance Expense for $600.