单选题 Mr. Wong paid ＄3,000 in advance for insurance on 1 December 2001 and debited it to Insurance Expense. No entries were made subsequently in 2001 or in 2002. The accounting period ends on December 31. As a result of this error ______. (a)2001 income was understated ＄2,000. (b)2002 income was understated ＄2,000. (c)2001 income was understated ＄3,000. (d)2002 income was understated ＄3,000.