Question Detail
Question
The sex-determination system in which males are XY and females XX is found in all: A. multicellular organisms B. animals C. vertebrates D. mammals
Correct Answer
Option D is the correct answer.
Detailed Explanation
The XY sex-determination system (with males being heterogametic XY and females homogametic XX) is characteristic of most mammals. It is not universal in all animals or vertebrates (e.g., birds have a ZW system, where females are ZW and males ZZ).
Hint
This includes humans, mice, dogs, etc.