Final answer:
Jellyfish is the most likely organism to be diploblastic.
Step-by-step explanation:
Jellyfish is the most likely organism to be diploblastic. Diploblasts are animals that develop from two germ layers - the ectoderm and endoderm. This means that, during embryonic development, they only form two tissue layers. Jellyfish belong to the phylum Cnidaria, which includes other diploblastic organisms such as sea anemones and corals. These organisms have radial symmetry and exhibit characteristics such as tentacles and the presence of stinging cells called cnidocytes.