Identify the Rule That States That Income Has Been Realized

Identify the rule that states that income has been realized when a taxpayer receives the income and there are no restrictions on the taxpayer's use of the income (e.g., no obligation to repay the amount) :

A) Claim of right.
B) Constructive receipt.
C) Return of capital principle.
D) Wherewithal to pay.
E) None of the choices are correct.