Vector-borne transmission of an infectious organism occurs via:

• A. Smoke or dust.
• B. Animals or insects.
• C. Direct contact.
• D. Inanimate objects.

Answer: (B)

Vector-borne transmission happens when a living organism carries the infectious agent from one host to another. In this mode, the pathogen relies on a living vector, such as an animal or insect, to acquire the pathogen from an infected source and then transmit it to a new host—often through a bite or contact. Examples include malaria spread by mosquitoes, Lyme disease by ticks, and dengue fever by Aedes mosquitoes. This living intermediary is the defining feature.

Smoke or dust involves environmental particles, not a living carrier. Direct contact requires physical interaction between people or contaminated surfaces, not the involvement of a living vector. Inanimate objects, or fomites, can spread pathogens when touched, but again without a living organism moving the pathogen between hosts.