the correct order for investment from lower RISK to Higher Risk would be:
Treasury Bond - Diversified Mutual Fund - Stock
Treasury bond is government issued, so the return is guaranteed by the government.
Diversified mutual fund, is a little bit risky, but since the investment is spread out through various type of business, the risk will be small
Stock, on the other hand, mean that you're betting on one business only, and it is really volatile depending on the market's condition