Disregarding any small business exceptions, for the current year, which of the following situations will result in a taxpayer owing a penalty for underpayment of taxes?

a.A married filing joint taxpayer had AGI of $160,000 and total tax of $35,000 in the prior year. For the current year, AGI is $175,000 and total tax is $40,000. He had no withholding in the current year and paid a total of $35,000 in estimated taxes.

b.The taxpayer owes $950 in taxes after his withholding was applied to his current year's tax return.

c.The taxpayer had AGI of $75,000 and total tax of $15,000 in the prior year. For the current year, his AGI is $62,000 and total tax is $12,500. He had no withholding in the current year and paid a total of $11,500 in estimated taxes.

d.The taxpayer had AGI of $100,000 and total tax of $20,000 in the prior year. For the current year, his AGI is also $100,000, but his total tax is $15,000. His withholding amounted to $10,000, and he paid $6,000 in estimated taxes.