Once the stationary phase is packed in the column, it is important that the solvent level not drop below the upper level of the stationary phase. Why?

A. Air molecules are so polar the entire mixture moves completely through the column.
B. If the stationary phase dries out, then the mixture will be permanently absorbed.
C. Air creates channels that may cause all of the components of the mixture to travel down the column at the same rate.
D. Atmospheric moisture can dissolve the stationary phase.