Exercises Draw data models for the following situations. In each case, make certain that you show the attributes and feasible identifiers. Show relationships and cardinalities.

a.A farmer can have many cows, but a cow belongs to only one farmer.

b. A university has many students, and a student can attend at most one university.

c. An aircraft can have many passengers, but a passenger can be on only one flight at a time.

d. A nation can have many states and a state many cities.