In an ER model, suppose relation R is a 1:N relationship from entity set A1 to an entity set A2. Assume that A1 and A2 participate totally in R and that the cardinality of A2 is greater than the cardinality of A1.
Which of the following is true?1
Every entity in A1 is associated with exactly one entity in A2
2
Every entity in A1 is associated with at most one entity in A2
3
Every entity in A2 is associated with exactly one entity in A1
4
Every entity in A2 is associated with at least one entity in A1