My only potential option if I have N100,000 to invest will be to buy and hodl Bitcoin. My reason is that I have an interest mainly in long-term investment since I already have a trade that gives me daily income. But to answer your questions.
Low risk investment: I will consider buying cheap land in a rural area and keeping it for years. I will resell it when the price appreciates. Some farmlands in the interior area of my state can cost less than the amount stated above.
Medium risk investment: I will invest the money in buying of raw matreials such as cassava and using it to process garri that will be sold. Garri can be sold profitably in urban areas.
High-risk investment: it will be investing all in Bitcoin. Since the price is volatile, the coin is a high risked business. But it will be my first choice because I am not seeking instant profit.