[tex]f(x)=4x-6\\\\D=\{2,\ 4,\ 6\}\\\\R=\boxed{?}\\\\Calculate\ values\ of\ f(2),\ f(4)\ and\ f(6).\\\\Put\ the\ values\ of\ x\in\{2,\ 4,\ 6\}\ to\ the\ equation\ of\ the\ function:\\\\f(2)=4(2)-6=8-6=2\\f(4)=4(4)-6=16-6=10\\f(6)=4(6)-6=24-6=18\\\\Answer:\ The\ range\ is\ equal\ R=\{2,\ 10,\ 18\}\to\boxed{D.}[/tex]