You are presented with the question "injury of the lungs can be caused by what" and the following answer choices: - running - wind and erosion - breathing - cigarettes - Pesticides - bacterial infection - smoking cigarettes - foggy air Now knowing that pneumonia may be caused by an infection or injury of the lungs and common bacterial pneumonia can be caused by Streptococcus pneumonia or Klebsiella pneumonia , choose the best answer.
A:
bacterial infection