The bar is only "might"
You do not have to show that an answer would convict you. If it might expose you to a charge, that question can be declined. Almost nobody is ever told the gate is that wide.
Free · Singapore
They can ask you anything.
You do not have to answer everything.
Almost nobody walks into a first police interview knowing where the line sits. So they answer everything, for three or four hours — and those answers become the case against them. I have lost count of the people who told me they pleaded guilty in the end. Not because they were guilty. Because by then they had already said too much, and fighting it costs money they did not have.
Here is the part nobody tells you. Under s 22(2) of the Criminal Procedure Code, the test is only whether an answer might expose you to a charge — not whether it would. That gate is far wider than almost anyone realises, and it has been standing open the whole time.