A quick question on Afrikaans

Hi everyone!

I have a quick question about question elements in Afrikaans language and I’d be very grateful for the intuitions of native speakers.

Could you tell me whether the following sentences sound natural to you?

1. Hoekom op aarde sou ek so iets doen?

2. Hoekom sou ek op aarde so iets doen?

3. Waarom op aarde sou ek so iets doen?

4. Waarom sou ek op aarde so iets doen?

Even a very brief reply like “1 yes, 2 no”, etc., would already help me a lot.

Many thanks in advance!