QUESTION 9 1 points An unmarried taxpayer with AGl of $120,000 in 2017 has a tax liability of $21,000. The taxpayer's 2018 AGI and tax liability are $175,000 and $31,000, respectively. To avoid any penalty for underpayment of estimated tax in 2018, the minimum amount the taxpayer must prepay during 2018 is: O $21,000 O $23,100 O $27,900 O $31,000 O $34,100