What is described as the invasion of body tissues by disease-causing pathogens?

Infection is defined as the invasion of body tissues by disease-causing pathogens, such as bacteria, viruses, fungi, or parasites. Once these pathogens enter the body, they can multiply and potentially lead to illness by damaging tissues and triggering the immune response. This process illustrates the ability of pathogens to not only enter but also establish themselves within the host's body, causing various symptoms of disease.

The other terms provided in the options refer to different concepts:

• Contamination refers to the presence of unwanted substances or pathogens on surfaces or in the environment, but it does not imply that these pathogens have invaded the body's tissues.

• Infestation typically relates to the invasion of larger organisms, like parasites (e.g., lice or worms), onto the host but doesn't address the microbial invasion that directly causes disease.

• Inoculation refers to the introduction of antigenic substances into the body to stimulate an immune response, particularly in the context of vaccinations, rather than an invasion of diseases.

Understanding these definitions helps clarify why infection is the correct response, as it directly encompasses the idea of pathogens invading and affecting bodily tissues.