Scientists use the term "atomic model" to describe the atom. What is a reason why it is called a model? *
A. atoms are too small to see directly
B. the atomic model is a representation of what scientists believe the atom to be C. models can continuously be modified as new discoveries are made
D. All of the above are true.

All of the above are true.

A is correct, because, well. We can’t see atoms directly, at least not with our current levels of technology.

B is correct because a model is a representation of something by nature.

C is correct because our knowledge of the atom is still growing, and as we still don’t know about some future atomic developments, it’s called a model so that there’s still flexible room for new discoveries.

Hope this helps!

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.