B. HINT: the last digits of the sequence, , , , . . . , . . . n = 1, 2, 3, 4, 5, 6, 7, 8, . . . form a periodic sequence 7, 9, 3, 1, 7, 9, 3, 1, . . . . So, if you were born in 2001, then the last digit of the number is 7; if you were born in 2002, then the last digit of the number is 9; if you were born in 2003, then the last digit of the number is 3; if you were born in 2004, then the last digit of the number is 1;