Which is the class of cnidarian that is characterized by having a dominant medusa stage and four gastric pouches?

scyphozoa

Explanation:cniderians are aquatic animals.they have radial symmetry, that is they can be divided into two halves through any plane.

Cniderians may have nematocyst,which are stinging cells.

They have two forms,which are polyp and Medusa .

There are four classes of cniderians;hydrozoa, scyphozoa,cubozoa and anthozoa.

Scyphozoa are predominantly medusa,which is umbrella shaped.they are jelly fishes.

They have four or eight oral arms.

They possess four gonads and four gastric pouches .an example is the Aurelia.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.