Sam started a new job in July of last year. He received a total of 12 paycheques last year totaling $19,600. On January 7th of this year, Sam received a paycheque for $1,640 covering the two week period from December 24th of last year to January 7th of this year. In addition, on December 23rd of last year, Sam was informed that he would be getting a bonus of $2,000 in respect of his performance during last year, but that the bonus would not be paid until February 2nd of this year. What was Sam's taxable employment income for last year?

a) $19,600

b) $20,420

c) $21,600

d) $22,420