Editor's note: The following are questions received from viewers of "Mad Money," seen every day at 6 p.m. EST on CNBC. What is your opinion on Whole Foods Market (WFMI) now that it is off about 20% from its highs? -- Mike from Florida James J. Cramer: Even though the retailer's fundamentals still look strong, this is one falling knife that I wouldn't try to catch. The stock is trading at 47 times expected full-year earnings, and I believe that Wal-Mart's ( WMT) push into the organic grocery market adds just one more potential land mine to the equation. Want more Cramer? Check out Jim's rules and commandments for investing from his latest book by clicking here.