Answer:
c. Debit to Fair value adjustment for $30,000
Explanation:
The first step of accounting process is Journal entry and it is made to record the transactions for process of book keeping, it defines the accounts involved and effects of  transactions on the account by debit or credit.
As the bond price is amortized earlier by 5,000 then its net realizable value was $195,000 ( $200,000 - $5,000 ). on December 31, year 3 the fair value adjusted to $225,000. so the adjusted value will be $30,000 ( $225,000 - $195,000 ). The journal entry is as follow Â
                                  Dr.        Cr.
Dec 31, year 3
Fair value adjustment account        30000
Unrealized gain on available for sale securities     30000