What is a common route of transmission that involves blood from an infected animal?

The correct choice highlights direct contact as a common route of transmission that involves blood from an infected animal. In many cases, diseases can be transmitted through direct exposure to the body fluids, particularly blood, of an infected animal. This includes situations where an individual may be bitten, scratched, or come into contact with open wounds or mucous membranes that have been exposed to an infected animal's blood.

Direct contact facilitates the transfer of pathogens such as viruses, bacteria, or parasites that can lead to illness in humans or other animals. For example, rabies is often transmitted through the bite of an infected animal, which involves saliva and can be considered a form of direct contact with infectious material.

The other choices involve different transmission methods. Vector-borne transmission generally refers to diseases spread by organisms like mosquitoes or ticks, which do not directly involve the blood of an infected host in the same way that direct contact does. Fecal-oral transmission and airborne transmission are also distinct routes that occur via ingestion of contaminated material or inhalation of pathogens in the air, respectively, and do not relate to blood transmission.