Question

What began as a single fertilized egg has just separated into two distinct eggs. this indicates the formation of _____ twins that has occurred during the _____ period of development?

Answer 1

The above statement indicates the formation of monozygotic twins that has occurred during the blastocyst period of development.

Explanation:

When a single fertilized egg has just separated into two distinct eggs, it indicates the formation of monozygotic twins that has occurred during the blastocyst ( 2 celled) period of development  

Usually a female during the mensural cycle releases one egg from one of the fallopian tube, whereas 1% of the females release 2 eggs from the fallopian tubes causing the formation of dizygotic twins but if it is from a single egg then they are said to be mono-zygotic twins.