$1)$ Draw data models for the following entities. In each case, In each case, think about the names you give each entity and make certain that you show the attributes and feasible identifiers:

a$)$ Farmers can own cows or share cows with other farmers.

b$)$ A track and field meet can have many competitors, and a competitor can participate in more than one event.

c$)$ A patient can have many physicians, and a physician can have many patients.

d$)$ A student can attend more than one class, and the same class can have many students.

e$)$ The Marathoner, a monthly magazine, regularly reports the performance of professional marathon runners. It has asked you to design a database to record the details of all major marathons $($e$.$g$.,$ Boston, London, and Paris$).$ Professional marathon runners compete in several races each year. A race may have thousands of competitors, but only about $200$ or so are professional runners, the ones The Marathoner tracks. For each race, the magazine reports a runner's time and finishing position and some personal details such as name, gender, and age.

$2.$ Please see the attached to for the question

$3)$ Why do you have to create a third entity when you have an m:m relationship?