isolating a chemical element

[ostap77]

"The fact that radium "had been/was ??"discovered by Marie Curie gave her the possibility of isolating other radioactive elements."

OR

"The fact that Marie Curie "had discovered/discovered radium gave her the possibility to isolate other radioactive elements."

Which one sounds better?

 

[5jj]

"The fact that radium had been/was discovered by Marie Curie gave her the possibility of isolating other radioactive elements."

"The fact that Marie Curie had discovered/discovered radium gave her the possibility to isolate other radioactive elements."

Which one sounds better?

The past perfect.