Considering the following tables, $\_\_\_\_\_\_\_\_$ is a primary key.

Student Table $$ Professor Table $$ Class Table

SID Name Expected Graduation Year $$ PID Name Tenure Year $$ ID Name PID

$123$ Smith $2017$ ABC Jones $1995$ MGT$101$ Intro to Management ABC

$234$ Jones $2018$ DEF Brilliant $2000$ BUS$101$ Intro to Business ABC

$567$ Barilla $2018$ GHI Genius $2000$ MGT$201$ Intermediate Management GHI

Question $10$ options:

Professor Table: Name

Class Table: PID

Student Table: Expected Graduation Year

Student Table: ID