What is the "alternative minimum tax" that must be paid by a taxpayer filing a joint return, if the taxpayer has taxable income of $95,450, adjustments to taxable income of $29,000, tax preferences of $51,000, and an income tax before the alternative minimum tax of $6,000?

a. $21,000

b. $16,133

c. $10,133

d. $0

e. None of these