All three are acceptable. A couple of thoughts...
- Savings accounts will have the lowest interest rates of the ones listed, but virtually no risk.
- Your could consider money market funds, if interest rates rise, you'll capture that rise faster than if you have a savings account
- You could do a CD ladder which would involve CDs with varying maturity dates between now to three years from now. You'll get a higher return on the longer term CDs and if interest rates go up, you will be able to reinvest the short term CDs at a higher rate
- Short-term bonds will most likely get the highest return. However, if interest rates go up, the bonds will go down in value. It won't be as extreme as long-term bonds, but it will occur.