Consider a schema with two relations R(A, B) and S(B, C) where all values are integers. Make no assumptions about keys. Consider the following three Relational Algebra expressions: A. A,C(RB=1(S)) B. A(B=1(R)) C(B=1(S)) C. A,C(A (R) B=1(S)) Two of the three expressions are equivalent (i.e., produce the same answer on all databases), while one of them can produce a different answer. Which query can produce a different answer? Give the simplest database instance you can think of where a different answer is produced