Step 1: Understanding Mammalian Reproduction Types.
Mammals are typically divided into three categories based on their mode of reproduction: monotremes, marsupials, and placental mammals. Monotremes are the only mammals that lay eggs.
Step 2: Identifying the Animals Listed.
Macropus includes kangaroos and wallabies, which are marsupials, not egg-layers.
Balaenoptera includes the blue whale and other large whales, which are placental mammals.
Panthera tigris, or the tiger, is also a placental mammal.
Step 3: Recognizing the Correct Answer.
Ornithorhynchus, known as the platypus, is one of the few monotremes alongside echidnas. The platypus is distinctive for its duck-bill and webbed feet and is one of the very few mammals that lay eggs.
If the roots of $\sqrt{\frac{1 - y}{y}} + \sqrt{\frac{y}{1 - y}} = \frac{5}{2}$ are $\alpha$ and $\beta$ ($\beta > \alpha$) and the equation $(\alpha + \beta)x^4 - 25\alpha \beta x^2 + (\gamma + \beta - \alpha) = 0$ has real roots, then a possible value of $y$ is: