In 2013, Maria (who files as a head of household) reported regular taxable income of $115,000. She itemized her deductions, deducting $5,000 in charitable contributions and $3,000 in state income taxes. She claimed exemptions for herself and her son, Henry, ($3,900 each). What is Maria's alternative minimum taxable income?

a. $115,000

b. $118,000

c. $122,800

d. $125,800