Dave a property developer, completed his SA100 income tax return and submitted it by the filing deadline. Dave recently confessed to his advisor that he had deliberately hidden and not declared E15.000 of other income he earned during the tax year. Dave followed his advisor's advice and immediately voluntarily notified HMRC of the understated tax. What MAXIMUM penalty could HMRC charge Dave for understating his tax? Select one: a. 100% of underpaid tax b. 15% of underpaid tax C 309 of underpaid tax d. 70% of underpaid tax