Create an ER diagram for each of the following descriptions:

$($a$).$ Each company operates four departments, and eachdepartment belongs to one company.

$($b$).$ Each department in part $($a$)$ employs one or moreemployees, and each employee works for one department

$($c$).$ Each department in part $($a$)$ employs one or moreemployees, and each employee works for one department.

$($d$).$ Each employee in part $($c$)$ may or may not havean employment history.