Synovial fluid select one: a. is a double layer of tissue that encloses a joint. b. is a thin lubricating film covering the surface of a joint. c. provides a smooth surface where bones meet. d. is a layer of tissue that is continuous with the periosteum. e. lines the joint everywhere except over the articular cartilage.

The correct answer will be option- B.

Explanation:

Synovial fluid is a clear slippery fluid which is present in the synovial cavity.

The synovial fluid helps the nourishment as it provides nutrients to the and oxygen to the hyaline cartilage of the bones as well as the lubrication of the cartilage surfaces due to the viscous nature like oil which lubricates the piston.

This smooth surface facilitates the smooth and painless movements between the bones, therefore, the Option-B is the correct answer.

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.