Final answer:
A germ that can cause disease or infection is correctly termed a pathogen, which can be bacteria, viruses, or other microorganisms that cause diseases.
Step-by-step explanation:
A germ that can cause disease or infection is called a pathogen. In the context of this discussion, a pathogen is an agent, often a microorganism such as bacteria or viruses, that invades another organism and causes disease. The term germ is frequently used interchangeably with pathogen in a more casual setting, but the scientific community prefers pathogen when referring to these disease-causing agents.
It is important to understand that not all microorganisms are harmful; in fact, many are beneficial to human health, and only a relative few are pathogenic. These disease-causing microbes can be transferred from one person to another, making diseases caused by them contagious. The immune system plays a crucial role in defending against these pathogens and preventing infections.
Therefore, the correct answer to the student's question is b. pathogen.