【单选题】

The vegetative forms of most bacteria are killed by drying in air, although the different species exhibit pronounced differences in their resistance. The tubercle bacillus is one of the more resistant, and vibrio cholera is one of the more sensitive to drying. In general, the encapsulated organisms are more resistant than the non-encapsulated forms. Spores are quite resistant to drying; the spores of the anthrax bacillus, for example, will germinate after remaining in a dry condition for ten years or more. The resistance of the pathogenic forms causing disease of the upper respiratory tract is of particular interest in connection with airborne infection, for the length of time that a droplet remains infective is a result, primarily, of the resistance of the particular microorganism to drying.

It may be inferred from the passage that ______.A．bacteria can be most easily killed by removal of moisture.
B．drying out a house will eliminate the risk of airborne infection.
C．hot-air heating is better than steam heating because steam heating uses water.
D．none of the abov