Part $1$: Keys and Data Integrity

Below is a company database with three tables. Please try to understand all the tables and columns.

$1\mathrm{.}1$ For each table, identify the primary key and the foreign key$($s$).$ If a table does not have a foreign key, write None.

$1\mathrm{.}2$ Do the tables exhibit entity integrity? Answer yes or no$,$ and then explain your answer.

$1\mathrm{.}3$ Do the tables exhibit referential integrity? Answer yes or no$,$ and then explain your answer. Write NA $($Not Applicable$)$ if the table does not have a foreign key