If r is a relation in relational data model and a1,a2,..an are the attributes of relation r, what is the cardinality of r expressed in terms of domain of attributes?

(a) |R|<=|dom(A1)X dom(A2)..dom(An)|

(b) |R|>=|dom(A1)X dom(A2)..dom(An)|

(c) |R|=max(|dom(A1)|,|dom(a2)|,..|dom(An)|)

(d) |R|=min(|dom(A1)|,|dom(a2)|,..|dom(An)|)