Final answer:
The incorrectly spelled word is 'pnumonia'; the correct spelling is 'pneumonia'. Additionally, different pathogens such as Streptococcus pneumoniae and Mycoplasma pneumoniae cause different types of pneumonia.
Step-by-step explanation:
The word that is spelled incorrectly is b) pnumonia. The correct spelling is d) pneumonia, which refers to a respiratory condition that involves an infection of the lungs. This is important to differentiate from other diseases caused by various microbes. For instance, Streptococcus pneumoniae is a bacterium that can cause bacterial pneumonia, whereas Mycoplasma pneumoniae is associated with a milder form of the illness often called "walking pneumonia". Furthermore, Coxiella burnetii is the cause of Q fever, not pneumonia. These pathogens are distinctly different from each other and cause various diseases.