28: Rock samples taken from the remains of an asteroid about twice the size of the 6-nuke-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.

A: has been dated to be 3.47 billion years old and thus is

B: has been dated at 3.47 billion years old and thus

C: have been dated to be 3.47billion years old and thus are

D: have been dated as being 3.47 billion years old and thus

E: have been dated at 3.47 billion years old and thus are

请教此题选C还是选E?请一定指教,多谢!