In a frog embryo, gastrulation A) produces a blastocoel displaced ...

[sammy]

In a frog embryo, gastrulation
A) produces a blastocoel displaced into the animal hemisphere.
B) occurs along the primitive streak in the animal hemisphere.
C) is impossible because of the large amount of yolk in the ovum.
D) proceeds by involution as cells roll over the lip of the blastopore.
E) occurs within the inner cell mass that is embedded in the large amount of yolk.

[clippers!]

For sure it has to be D Mark as solved once you're done!