iMac 27 Late 2009 - 3.06 GHz - Replace Video Card Compatible

Hello,

my video card ATI Radeon HD 4670 256 MB is gone!

My iMac model is: iMac 27" Late 2009 EMC 2309 - 3,06 GHz Intel Core 2 Duo

I need to buy another video card but I am not sure which video cards are compatible:

1) ATI Radeon HD 5750 1GB GDDR5

2) ATI Radeon HD, 4850 512MB

3) ATI Radeon HD, 5670 512MB GDDR3 SDRAM

4) AMD Radeon HD 6970

5) Apple IMac AMD Radeon HD 6970M 2GB Video Graphics Card iMac 27" 2011 661-5968

Please help me... Thanks!

;)