Nina Events Organizers manages various big corporate conferences around the city. On January 3, 2022, they charged a special price of $1,000 for one of their clients, who prepaid for five identical events this year and next year. Assuming the company has a December 31 year-end and only two events out of five have been held before the end of the year, which of the following journal entry is required to record this transaction on January 3, 2022? 

a. Debit Unearned Revenue $1,000; credit Service Revenue $1,000

b. None of the choices listed

c. Debit Cash $1,000; credit Unearned Revenue $1,000

d. Debit Cash $400; credit Service Revenue $400