a calico cat shows both the traits for orange fur and black fur. what kind of allele expression is this?

The allele expression in this example is codominance , more specifically a form of sex‑linked codominance where both the orange and black fur traits are expressed in distinct patches on the cat’s coat.

In codominance, both alleles are fully and visibly expressed rather than blending together, which is why a calico cat has separate orange and black areas instead of a single intermediate color.