"I think that she loves me."
Translation:Tôi nghĩ cô ấy yêu tôi.
In this course, we've limited the personal pronouns and you can only use "tôi" for "I" and "me". Other answers won't be accepted. Please review the Tips and Notes of skill Basics 1 to recall this.
It is saying Tôi nghĩ cô ta yêu tôi as a second accepted answer - I have never seen cô ta before!
They may have included rằng since your post, but I just used Tôi nghĩ rằng cô ấy yêu tôi and it was accepted, so những ngày hạnh phúc.