'Simple' is the word used in the link.
The others are also correct.
Note that 'Tell me why can't I choose them'is not a question, so it needs a full stop.
The word 'please' at the beginning or end would make it sound like a request rather than a command.
It's infuriating how this thing sometimes starts a new line in all the wrong places, despite how many times you try to edit your text. It makes us look stupid.
- For Teachers