It depends whether you were speaking about the subject before. Then you use ona, ona, oni and similar. But in this case you can also use "Je to..." or "Jsou to...". (Ony) Nejsou malé holky. and Nejsou to malé holky. are pretty much equal.
If you see something for the first time, you use "To je...".
I say again: It is accepted.
If any of your answers is not accepted and should be, then:
1. check for typos, missing words and other obvious errors
2. use the report button "My answer should have been accepted"
Do not report these answers in the discussion, ask if you really want to ask a real question.