Which one of the following is not correct? (a) Relational algebra provides a collection of…

Which one of the following is not correct? (a) Relational algebra provides a collection of operations that can actually be used to build some desired relation; the calculus provides a notation for formulating the definition of that desired relation. (b) In relational algebra, one specifies what operations must be executed while in relational calculus, the specification of operations is left to the system. (c) Relational algebra is procedural while relational calculus is nonprocedural. (d) Using relational calculus one may specify more complex queries than using relational algebra.