An arthropod in whose body an infectious organism develops/multiplies before infecting a host is termed ______.

• A. A vector
• B. A host
• C. A parasite
• D. A pathogen

Answer: (A)

The term you're looking for describes an organism that transmits infectious agents to other organisms. When an arthropod serves as a vector, it not only carries the infectious organism but also provides an environment for it to develop and multiply before passing it on to a suitable host. This role is crucial in the transmission cycle of many diseases, such as malaria or Lyme disease.

In contrast, a host refers to an organism that harbors a parasite or pathogen, typically becoming ill as a result. A parasite is an organism that lives on or in a host and derives nutrients at the host's expense, while a pathogen is a microbe or infectious organism that causes disease. These distinctions highlight the specific role of vectors in maintaining and spreading infectious organisms in the environment.