Which label belongs in the area marked y?
connor drew a venn diagram to compare sponges and
cnidarians.
sponges
cnidarians
are covered in pores
reproduce by budding
live in fresh water
have a network of nerve cells

Among Sponges and Cnidarians, the difference among given facts is in "Have a network of nerve cells".

Explanation:

Both Sponges and Cnidarians have pores, they reproduce by buddings, and they live in freshwater. The major difference in both organisms is that: cnidarians have very simple nervous system made of sensory nerves that are arranged in the form of neural network. On the other hand, sponges are simple multicellular organisms without any neural network at all. In fact, they are the only multicellular organisms (animals) without a nervous system.

answer; polycythemia is the correct answer;

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.