**Core Concept**
Rabies is a viral disease caused by a lyssavirus that affects the nervous system of mammals, including humans. The virus is primarily transmitted through the saliva of infected animals, usually through bites.

**Why the Correct Answer is Right**
The transmission of rabies is primarily through the bites of infected animals, which introduce the virus into the wound. The virus then travels to the central nervous system (CNS), where it replicates and causes severe inflammation of the brain and spinal cord. This is because the rabies virus is highly neurotropic and has a predilection for the neurons of the CNS.

**Why Each Wrong Option is Incorrect**
**Option A:** Aerosol transmission of rabies is not a recognized mode of transmission. While the virus can be present in the saliva of infected animals, it is not transmitted through the air.
**Option B:** Organ transplantation from an infected donor can transmit rabies, but this is an extremely rare occurrence. The risk is higher if the donor had symptoms of rabies at the time of death.
**Option C:** Contact with infected animals, such as touching or petting them, is not a recognized mode of transmission. However, if the animal bites, the risk of transmission increases significantly.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the incubation period of rabies can range from a few days to several years, making it challenging to diagnose. Prompt medical attention is crucial if exposed to an animal that may be infected.

**Correct Answer: A. Aerosol transmission of rabies is not a recognized mode of transmission.**