To find Helene's elevation at base camp after descending 46 feet from an elevation of 33 feet above sea level, you can perform the following calculation:
Starting elevation: 33 feet
Descent: 46 feet
Base camp elevation = Starting elevation - Descent
Base camp elevation = 33 feet - 46 feet
Base camp elevation = -13 feet
This means Helene is 13 feet below sea level.
Thus, the correct response is: 13 feet below sea level.