i got question A &B i just can’t get C

Step 1
The domain refers to all values that go into a function. The range refers to all the values that come out.
Step 2
Find the domain
[tex]D=\mleft\lbrace2007,2008,2009\mright\rbrace[/tex]Step 3
Find the range
[tex]R=\mleft\lbrace234300,213200,\text{ 212,200}\mright\rbrace[/tex]