Defining Infectious Diseases

Steps:

• Recall that infectious diseases involve transmission between organisms.
• Identify key causes: pathogens like bacteria, fungi, protoctists, or viruses.
• Eliminate options describing non-transmissible or non-pathogen causes.
• Match the definition to option D.

Why D is correct:

• Infectious diseases are defined as those caused by pathogens (bacteria, fungi, protoctists, viruses) that invade the body and can spread.

Why the others are wrong:

• A describes non-communicable diseases, which do not spread person-to-person.
• B describes genetic disorders, inherited via DNA mutations.
• C describes deficiency diseases, resulting from nutritional shortages like vitamin lacks.

Final answer: D