All of the statements about sponges are correct except:
a. mesohyl is mostly noncellular and provides structural support.
b. sponges are among the most primitive organisms to have developed reproductive organs.
c. gas exchange of oxygen and carbon dioxide occurs through diffusion.
d. choanocytes have flagella that beat in a coordinated fashion.

The correct answer is b. Sponges are among the most primitive organisms to have developed reproductive organs.

Explanation:

Sponges are multi-cellular animals that are one of the members of Porifera phylum. These organisms are very primitive organisms so their body cells are not organized into a tissue so it lacks tissue or organ level of organization.

Developed reproductive organs are present in the organisms which have a higher level of body organization like mammals, reptiles. These organs produce and store gametes which helps in fertilization.

So as sponges lack tissue and organ level of organization it does not have reproductive organs and reproduce through budding or gamete fusion. They produce gametes through differentiation in their choanocytes.

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.