Like all valid scientific theories, modern cell theory
a. builds on the work of earlier scientists.
b. dismisses the theoretical developments of other scientists.
c. is complete and final as compared to earlier versions.
d. relies on the development of modeling techniques to progress

so your answer is:

builds on the work of earlier scientists

:)

The right answer is A.builds on the work of earlier scientists.

The cellular theory appeared in the 19th century, it consists of three principles:

1) All living organisms are made of at least one cell.

2) The cell is the basic organizational unit of life.

3) All cells come from other living cells

The cell is the structural and functional unit of an organism.

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.

lysosome is this part of the cell is surrounded by a very thick outer membrane to protect the rest of the cell from its strong enzymes.