Kingston Companys bank reconciliation for the month of November follows: Balance per bank statement, 11/30 $18,040 Add: Deposit in transit 4,150 $22,190 Less: Outstanding checks $6,300 Bank credit recorded in error 20 (6,320) Balance per books, 11/30 $15,870 Data for the month of December follows: Per bank: December deposits $26,100 December disbursements 22,420 Balance, 12/31 21,720 All items that were outstanding as of November 30 cleared through the bank in December, including the bank credit. In addition, $2,500 in checks were outstanding as of December 31. What is the balance of cash per books at December 31? a. $19,240 b. $24,220 c. $21,720 d. $19,220