How many embryonic and adult tissue layers are found in jellyfish, hydras, and sea anemones?
a. 1
b. 2
c. 3
d. 4

The answer is letter B.

There are 2 embryonic and adult tissues found in jellyfishes, hydras, and sea anemones. This is caused by the formation of a germ layer—a group of cells in the embryo that interact with each other while forming all organs and tissues. Germ layers develop through the process of gastrulation in the early embryonic life. The three organisms mentioned have two primary germ layers which gives them a radial symmetric structure classifying them as Dipoblastic organisms.