Question

Animals giving birth to young ones are
A. Viviparous
B. Oviparous
C. Triploblastic
D. Coelomate

Answer 1

Hint: In some animals fusion of gametes (fertilization) occurs outside the female body is called external fertilization. The embryo develops and it matures in the external environment. Whereas, in some animals fertilization is internal. Animals with external fertilization lay eggs. Some animals give birth to young ones in them internal fertilization is a rule.

Complete answer:
Some animals lay eggs called oviparous animals. Examples of oviparous animals are amphibians, reptiles, birds. In these animals, laid eggs later develop into young ones. Whereas, some animals give birth to young ones. The animals which give birth to young ones are called viviparous animals. Humans and other mammals are examples of viviparous animals.
Let us have a look a bit more the process of development of their embryo in viviparous animals:
In viviparous animals, fusion of sperm, a male gamete and egg or ova, a female gamete takes place inside the body. After fertilization, zygote is formed. Zygote undergoes a series of mitotic divisions to form embryos. The development of the embryo too occurs inside the female reproductive system. Once the fetus develops and mature, the mother delivers the baby. During embryonic development, the embryo obtains the nutrients directly from the mother through placenta.

Thus, option A. viviparous is the correct answer.

Additional information:
Mammals are generally viviparous, giving birth to young ones, but the duck-billed platypus and spiny anteaters are the mammals which lay eggs (oviparous).

Note: The period between fertilization and birth of offspring in viviparous animals is called the gestation period. The duration of gestation period varies according to species. In cats and dogs, it is 2 months, in humans it is 9 months and in elephants it is as long as 22 months.