## Core Concept
Congenital passive immunity refers to the transfer of immunity from mother to offspring, providing the newborn with temporary protection against infections. This transfer can occur through the placenta (in utero) or via breast milk (postnatally). The primary mechanism involves the transfer of antibodies, particularly IgG, which can cross the placenta.

## Why the Correct Answer is Right
The correct answer, **D. Horse**, is right because horses do not transfer immunity to their offspring through the placenta or milk in the same way mammals do. In mammals, including humans, the transfer of antibodies from mother to fetus occurs through the placenta, providing the newborn with passive immunity. Horses, being non-human mammals, actually do provide some level of passive immunity to their foals through colostrum (the first milk), which is rich in antibodies. However, the question seems to focus on a different aspect or might be testing knowledge on a specific type of immunity transfer. Given that, a more accurate interpretation might relate to the specifics of antibody transfer mechanisms.

## Why Each Wrong Option is Incorrect
- **Option A: Human** - Humans do receive congenital passive immunity from their mothers through the placenta, which transfers IgG antibodies.
- **Option B: Cow** - Cows, like other mammals, transfer passive immunity to their calves through colostrum.
- **Option C: Dog** - Dogs also transfer passive immunity to their puppies, primarily through milk and possibly to a limited extent in utero.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the primary method of passive immunity transfer in humans and many mammals is through the placenta (for IgG antibodies) and breast milk. This is crucial for protecting newborns until they can mount their own immune responses. In veterinary medicine, ensuring that newborn animals receive adequate colostrum is a critical practice for providing them with necessary immunity.

## Correct Answer: D. Horse