Which of the following refers to twins that develop from a single fertilized egg?

Identical twins are formed when a single fertilized egg, known as a zygote, undergoes division and develops into two embryos. This means that these twins share the same genetic material, as they come from the same egg and sperm. Because of their origin from one single zygote, identical twins typically have the same sex and look remarkably alike, sharing the same DNA.

In contrast, fraternal twins arise from two separate eggs being fertilized by two different sperm cells. Therefore, they are genetically distinct from each other, just like typical siblings. Other terms such as half-siblings and sibling pairs do not specifically relate to the development of twins from a single fertilized egg. Half-siblings share only one parent, while sibling pairs can refer to any set of brothers and/or sisters, without the specific context of their origin from a fertilized egg.