An expression in the domain relational calculus is of the form

• A. {P(x1, x2, . . . , xn) | < x1, x2, . . . , xn > }
• B. {x1, x2, . . . , xn | < x1, x2, . . . , xn > }
• C. { x1, x2, . . . , xn | x1, x2, . . . , xn}
• D. {< x1, x2, . . . , xn > | P(x1, x2, . . . , xn)}