The correct option is D All of the above
After fertilization, zygote undergoes cleavage divisions forming blastula and further divisions result in the formation of gastrula. The endoderm (of the gastrula) surrounds a cavity, called as the archenteron, which has an opening to the exterior at the point at which invagination occurs and this opening is called blastopore. The archenteron eventually becomes the cavity of the digestive tract. Thus, archenteron is the primitive enteron or digestive cavity of a gastrula. It is also known as primitive gut or gastrocoel.
So, the correct answer is option D.