A taxpayer requests their employer to pay 5% of their salary directly to a charitable organization. The taxpayer will not exclude this amount from their gross income. Instead, they will include their entire salary in gross income and will be entitled to a charitable deduction for the amount paid to the charity. The principle that dictates this treatment is the:

a. return of capital principle.

b. wherewithal to pay.

c. assignment of income doctrine.

d. charitable directive principle.

e. constructive receipt doctrine.