Each of the following taxpayers received a state income tax refund in 2018.  In all cases, the taxpayer has a filing status of married filing jointly.  What amount of the refund is properly included in 2018 income?
a. Refund of $729; taxpayer did not itemize deductions in 2017.  
b. Refund of $591; taxpayer had $13,291 of itemized deductions in 2017.  
c. Refund of $927; taxpayer had itemized deductions of $13,000 in 2017.