Good question. I'm glad you asked.
Look at the investment options for the 401(k) account. They usually--not always--have an investment option that is relatively close to "cash". DOUBLE-CHECK with the administrators. Unfortunately, sometimes it's something like a totally unsecured money-market fund full of unsecured commercial paper.

Sometimes they also have something that (in theory) should rise as inflation rises. What you probably want to do, is invest in a combination of the "near cash" and the "inflation hedge". Most inflation hedges (gold, petroleum) are cheap right now. I'd probably go about 50-50 cash/inflation hedges.
To get more control over your retirement options, you might consider OPTING OUT. Stop contributing, and instead, contribute to a ROTH IRA. This is with AFTER-TAX dollars, but it's worth it, because then your accumulated earnings not only grow tax-free, but are distributed tax-free. This is a screaming bargain.
But first, make sure that you are qualified to contribute. That depends on your income. There is a phase-out threshold. I could probably look it up.
The preceding advice was offered on a goodwill basis and does not constitute advice to buy or sell securities. Do your own due diligence. You are responsible for any investment decisions that you make.
