Exercise 2) [relational algebra under the set-semantics] weight: 20% You are given three relations, R(A,B,C,D), S(C,D,E,F) and T(E,F,G,H), having respectively nr, ns and nt tuples. a) What is the maximum number of tuples that you may find in relation Q defined as follows? Q:= R An San T Justify your answer. b) Use relational algebra and the set-inclusion operator (C) to express the constraint {C,D} in relation S is a foreign key from relation R