In substitution type of questions, some particular objects are assigned code names. Then a question is asked that is to be answered in the code language.
If orange is called butter, butter is called soap, soap is called ink, ink is called honey and honey is called orange, which of the following is used for washing clothes ?
Clearly, 'soap' is used for washing the clothes.
But, 'soap' is called 'ink'.
So, 'ink' is used for washing the clothes.