Fossil discoveries suggest that an extinct river turtle survived the m

Fossil discoveries (N) suggest (V) that an extinct river turtle survived the meteorite -----------IC
, which killed off dinosaurs 65 million years ago.------------Non essential Modifier

--,which ---modifying meteorite hmm Looks ok.
But intended meaning is River turtle survived the thrash of a specific meteorite that killed the dinosaurs 65 million years ago.As per A, ',which' is simply describing a meteorite, making the modifier non essential. Therefore it's wrong.

A) meteorite, which killed off dinosaurs 65 million years ago ---Incorrect as mentioned above.

B) meteorite that had killed off dinosaurs 65 million years ago---Past perfect is not required.
--One may argue that 2 events occurred i.e. dinosaurs killed and river turtle survived. But were these events happened one after another? No.

C) meteorite that killed off dinosaurs 65 million years ago
--That is specifying the meteorite. Which meteorite? The one that killed dinosaurs.
--Correct.

D) meteorite, which had killed off dinosaurs 65 million years ago.
--,which and had (Same reasoning as A and B)

E) meteorite killing off dinosaurs 65 million years ago
--Looks like turtle survived by killing off dinosaurs
--killing (present continuous) is incorrect.