Horses and donkeys can mate, but they produce a mule, which is always a sterile animal.This means that they cannot produce viable offspring and are square olated. reproductively geographically temporally

The correct answer is "reproductively."

When horses and donkeys mate, they produce a mule, which is always a sterile animal. This means that they cannot produce viable offspring and are reproductively isolated. Reproductive isolation is a mechanism that prevents different species from interbreeding and producing fertile offspring. In this case, the mule is a hybrid animal that is sterile, meaning it cannot reproduce and pass on its genes to the next generation. This reproductive barrier prevents horses and donkeys from exchanging genetic material and maintaining distinct species identities.