Upon asking I got the rest of the information needed to answer this question.
-> Which one becomes a repeating decimal?
Your answer is D. 1/9.
1/9 = 0.111111111111111111111111111111111 ... or 0.1 repeating. It can be written with a line over the 1 asyou can see in the attached.
This means that D is the answer to your question.