All microbial diseases are blank______, but they are not all blank______. Which pair of terms correctly completes the sentence?

• A. infectious; contagious
• B. viral; bacterial
• C. contagious; infectious
• D. acute; chronic

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the meaning of the terms 'infectious' and 'contagious'. 'Infectious' diseases are caused by pathogens such as bacteria, viruses, fungi, or parasites and can be transmitted to a host. 'Contagious' diseases are a subset of infectious diseases that can be spread easily from one person to another, typically through direct contact or close proximity.
2. Step 2: Recognize that all microbial diseases are caused by microorganisms, so they are all 'infectious' because they involve pathogens that can infect a host.
3. Step 3: Note that not all infectious diseases are 'contagious' because some infectious diseases do not spread easily between people (for example, tetanus is infectious but not contagious).
4. Step 4: Evaluate the other pairs of terms: 'viral; bacterial' refers to types of pathogens, not the nature of disease transmission; 'contagious; infectious' reverses the correct relationship; 'acute; chronic' refers to the duration of disease, not transmission.
5. Step 5: Conclude that the correct pair to complete the sentence is 'infectious; contagious' because all microbial diseases are infectious, but not all are contagious.