What is one major function of a fish's urogenital system?

The assertion that most fish are external fertilizers accurately reflects a central aspect of fish reproduction. In most fish species, fertilization occurs outside of the female's body, where the female lays eggs in the water, and the male subsequently releases sperm over them. This method allows for a greater number of offspring to be produced and relies on water as the medium for sperm to reach the eggs.

The characteristic of external fertilization is important, as it differentiates many fish species from terrestrial vertebrates, which often exhibit internal fertilization processes. Additionally, external fertilization aligns well with the aquatic environment, where buoyancy and mobility facilitate the spread and fertilization of eggs.

While discussing the other answer options in context, it's crucial to note that not all fish possess a urinary bladder, which is found in some species but is absent in many others. Similarly, fish do not exclusively excrete nitrogenous waste through the kidneys; they often convert ammonia to urea or excrete it in other forms via gills depending on the species and their habitat. Lastly, internal fertilization is rare in fish; it occurs in some species but is not the predominant reproductive strategy across the diverse fish taxa. This reinforces the correctness of the assertion regarding external fertilization as a major function of