The fertilized egg is called as a
A) Uterus
B) Ovary
C) Gametes
D) Zygote

Hint:The reproduction process of organisms is different in different groups of organisms. Some organisms undergo asexual reproduction some reproduce sexually. During sexual reproduction they gametes undergo fusion and fertilization takes place. The fertilization process is also divided into internal and external according to the organisms.

Complete answer:
To answer this question, we should know about the fertilization process. Fertilization is the process in which the male sperm and female egg get fused to form a zygote that develops into a fetus inside the uterus. During this process the semen that ejaculates by the males while sexual intercourse comprise thousands of sperm cells. The sperm move towards the uterus and reach to the fallopian tube opening. From the thousands of sperm few can reach the fallopian tube. Now, the secondary oocytes produced from the matured graafian follicle of the ovary enter inside the fallopian tube where it gets fertilized and released from the ovary. The oocyte is surrounded by several sperms but it gets fertilized only by one sperm. The sperm enter in the secondary oocyte in meiosis II phase and completes the meiosis this results in the formation of egg. After this phase, within 48 to 72 hours the sperm and the egg fused and formed the zygote. There are two types of fertilization process; external fertilization and internal fertilization. In the external fertilization, the fusion of egg and sperm is carried out in open instead of any specialized organs and in internal fertilization; it takes place inside the female body after ejaculation through copulation. The fishes and the frogs are oviparous that means they lay eggs and they undergo external fertilization. Some of the fishes like whales, sharks, etc undergo internal fertilization.

Thus, the correct option is ‘D’. Zygote.

Note:The internal fertilization is more advantageous as in this process, the fertilized egg does not get dehydrated on land, the egg gets nourished and protected inside the female body and the fertilization of the egg is done by a specific male. But in external fertilization, though they lay many numbers of eggs, not all the eggs get fertilized due to many different factors.