Riga Works for Street Tacos LLC

Riga works for Street Tacos LLC. The basis for Riga's contribution under the Federal Insurance Contribution Act to help pay for benefits that will partially make up for her loss of income on retirement is

A) an equitable share of the employer's unpaid contribution.
B) the employee's annual wage base.
C) the employee's special job skills.
D) the employer's adjusted gross profits.