Question

Anne has been observing human embryos in different stages. She wants to study the gastrula phase. How will she find it?

Answer 1

Take a look at this picture:
http://upload.wikimedia.org/wikipedia/commons/d/d9/Blastula.png

We can see that the GASTRULATION phase is where we can see a GASTRULA,
with THREE different layers:

1. Ectoderm
2. Mesoderm
3. Endoderm

Anne just needs to look for these three layers.
When she sees them, she'll know that the embryo is in the Gastrula phase.

Answer 2

not c

Answer 3

for plato it was B