Final answer:
Legionella bacteria, which cause Legionnaires' disease, are spread through inhalation of mists or water droplets containing the organism; not by direct contact, bodily fluids, or typical airborne transmission.
Step-by-step explanation:
Legionella bacteria are spread primarily through mists/water droplets (option D). This pathogen, Legionella pneumophila, is the causative agent of Legionnaires' disease. It is commonly found in warm water environments and can thrive in human-made reservoirs such as air conditioning cooling towers, humidifiers, and fountains. When these reservoirs produce aerosols, the bacteria can become airborne and when inhaled, lead to infection. Outbreaks are often associated with large buildings where the air conditioning systems contain contaminated water. It is important to note that the transmission is not through direct contact, bodily fluids, or airborne respiratory droplets from an infected person, but from aerosolized water droplets containing the bacteria.