Fill in the blank with the correct preposition.
My father has invested a lot of money __________ fishing.

in

The correct preposition to fill in the blank is in. The preposition in can be used to indicate location or position, or it can be used to indicate involvement or participation in something. In this case, my father has invested a lot of money in fishing, which means that he has spent a lot of money on fishing equipment, trips, and other expenses related to fishing.

The other options are incorrect.

• For is used to indicate purpose or destination.
• On is used to indicate movement or placement above something.
• Into is used to indicate movement or placement inside something.