Which of the following institutions does not operate in the money market?

This question is a little bit tricky to answer because out of the 4 options provided only one is not a
participant in the (Nigeria) money market and that is the mortgage banks because mortgage loans
are usually not in short term of say 13months which makes it not fit into the money market
characterised by short term loans. The central bank, Money deposit bank and insurance companies
are all participant of the money market because they offer short term loans.