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?

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.

answer: b: experiments that showed that all cells are similar in how they metabolize and in their composition

explanation: