$1.$ Please identify the number of Habits a User can and must have $($min and max cardinality$).$

$2.$ What is the relationship between Checkin and Comment?

a$.$ One$-$to$-$one relationship

b$.$ One$-$to$-$many relationship

c$.$ Many$-$to$-$many relationship

$3.$ What are the attributes associated with the User entity?

Draw an ER diagram for each of the following situations.

$4.$ Each employee in a company must take at least one training course. An employee could take many training courses. A training course may be taken by many employees or may not be taken by any employee.