A disease that spreads from one person to another through direct or indirect contact is best described by which of the following terms?

Introduction / Context:
In human health and epidemiology, different terms are used to classify diseases based on how they spread and how they affect the body. One important classification is based on whether a disease can move from one person to another, especially through close contact, droplets, or shared surfaces. This question asks you to identify the most accurate term for a disease that spreads by contact. Knowing the meanings of common descriptors such as infectious, contagious, fatal, incurable, and degenerative helps you answer correctly.

Given Data / Assumptions:
- The disease spreads through direct contact, like touching an infected person, or indirect contact, like touching contaminated surfaces.
- We are asked for a term that highlights the mode of transmission, not the severity or curability of the disease.
- The options include words that describe how diseases spread, how serious they are, or how long they last.
- Only one option specifically describes diseases that spread easily from person to person by contact.

Concept / Approach:
An infectious disease is any disease caused by a pathogenic microorganism such as a virus, bacterium, or fungus. Many infectious diseases can spread between individuals, but some may not spread easily by casual contact. The term contagious is a more specific subcategory that describes infectious diseases that spread readily from person to person, often through direct contact, droplets, or shared objects. Fatal describes whether a disease can cause death, incurable describes whether it can be cured, and degenerative refers to gradual deterioration of tissues. Since the defining feature in the question is spread by contact, the most appropriate term is contagious.

Step-by-Step Solution:
Step 1: Focus on the phrase spreads by contact in the question, which directs attention to transmission mode. Step 2: Evaluate option A, infectious, which describes diseases caused by pathogens but does not always imply easy person to person spread. Step 3: Evaluate option B, fatal, which is about severity and death, not about how the disease spreads. Step 4: Evaluate option C, incurable, which describes whether a disease can be cured and is unrelated to contact based transmission. Step 5: Evaluate option D, contagious, which specifically refers to diseases that spread from person to person, often by direct or indirect contact. Step 6: Evaluate option E, degenerative, which refers to gradual deterioration of organs, as in some nervous system diseases, and does not imply contact spread. Step 7: Conclude that contagious is the best match for a disease that spreads by contact.

Verification / Alternative check:
You can verify this choice by recalling common examples. Diseases such as measles, chickenpox, and common colds are often described as highly contagious because they pass easily through contact or close proximity. On the other hand, conditions like cancer or diabetes are not called contagious because they do not spread from person to person. While they may be serious or even fatal, the lack of contact based transmission means they do not fit this term. This comparison confirms that contagious is the correct label for diseases that spread by contact.

Why Other Options Are Wrong:
Infectious, option A, is too general, because it includes all diseases caused by pathogens, including those that do not spread through simple contact, so it is not the most precise answer.
Fatal, option B, focuses on whether the disease can lead to death and does not say anything about how it spreads, so it cannot be correct here.
Incurable, option C, describes treatment outcome rather than transmission, so it does not answer the specific question about spread by contact.
Degenerative, option E, refers to slow deterioration of tissues and is used for diseases like Alzheimer type conditions; these are not typically spread from person to person by contact.

Common Pitfalls:
Students sometimes confuse infectious and contagious, using them as if they mean exactly the same thing. While all contagious diseases are infectious, not all infectious diseases are contagious in the everyday sense. Another mistake is to pick fatal simply because many contagious diseases can be serious, even though fatal has nothing to do with transmission mode. Paying close attention to the clue about contact in the question helps avoid these misunderstandings.

Final Answer:
Contagious is the correct term for a disease that spreads from one person to another through direct or indirect contact.