In endoscopy of uterine space embryo was revealed. It was not attached to endometrium. What is this stage of embryogenesis?

In endoscopy of uterine space embryo was revealed. It was not attached to endometrium. What is this stage of embryogenesis?

1.  Zygote


2.  Morula


3.  Gastrula


4.  Neurula


5.  *“Free blastocyst”