Final answer:
The ultimate cause of male cats responding to a female cat's urination during heat is the biological drive to reproduce and pass on genetic material, leading to behavioral adaptations such as fighting for the right to mate with the female.
Step-by-step explanation:
The ultimate cause of the male cats' response to the female's urinating behavior is related to reproduction. In this context, the ultimate cause refers to the biological impetus driving a particular behavior, which in this case is to reproduce and pass on genetic material to the next generation. This is distinct from the proximate cause, which would explain the immediate factors, like the chemical signals in the urine. The urine acts as such a signal, indicating that the female cat is in heat, prompting the congregation and competitive behavior of male cats. These male cats are driven by the genetic predisposition to spread their genes by mating with a receptive female, which in the animal kingdom, can be a strong driver for behavior. As a result, behavioral adaptation in the form of fighting amongst males to determine the most suitable mate arises.