A resident taxpayer spends most of their working year out of the state, but otherwise maintains a domicile within the state and frequently returns to their family. Assuming all of the income was earned in the other state in this scenario, what amount of income should be considered part of California gross income? Select one: a. All of it b. An amount apportioned to the days spent within and without the state c. None of it d. An amount apportioned between the relevant expenses compared between the out-of-state and in- state costs