Final answer:
Legionella and tetanus are infectious due to environmental exposure to bacteria, not from person to person, making them non-communicable diseases.
Step-by-step explanation:
Legionella and tetanus are examples of infectious but non-communicable diseases. These diseases cannot be spread from person to person, but rather are caused by environmental exposure (Option C). Tetanus, for instance, is caused by Clostridium tetani, which is found in soil and enters the body through wounds. It is not spread from person to person. Legionnaires' disease, caused by Legionella pneumophila, usually occurs when an individual inhales contaminated water droplets, not through person-to-person contact. Both diseases require specific environmental conditions to infect a host, making them non-communicable despite their infectious nature.