Underline every primary key, bold every foreign key, and italicize every possible candidate key for the following database. The driver_id is the driver license number, ssno is the social security number, rental_eq_id is the unique id for a rental equipment. Any additional assumptions have to be logical and realistic without changing the problem and its assumptions.

Assumptions: An employee can be a customer, a customer has to be a US citizen, and an equipment type has the same rental period.

employee (emp_id, driver_id, ssno, name, title, address)

payrate (emp_id, date, rate)

timecard (emp_id, date, hours)

emp_benefit (emp_id, start_date, benefit_id, ssno, ending_date)

benefit (benefit_id, type, benefit_name, description, cost)

customer (cust_id, name, address, city, state, driver_id, ssno)

equipment (bar_code, eq_name)

rental_eq_id (eq_id, bar_code, acquire_date, cost, rental_fee, available)

rental (cust_id, eq_id, rent_date, due_date, emp_id)