Which of these are viable ?

[Caseyjane14]

Day 7…
I’m having a hard time figuring out which are duds.
Obviously 1 there is no embryo, correct?

The rest I can see little the little black dot and veins, however, I can’t differentiate between air sacs and blood rings.

 

[BigBlueHen53]

Here's a video that might help you.

https://www.google.com/search?q=blo...ate=ive&vld=cid:cb2c4634,vid:rtbQt8Z-jBo,st:0