2. 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. 114,c(R OB=1(S)) b. 114(OB=1(R))x11c(Ob=1(S)) c. 114,c(IIA(R)X0b=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