Although choanoflagellates are fundamentally unicellular organisms, they possess genes that code for cadherins and integrins. Which of the following hypotheses regarding the function of these molecules in choanoflagellates is supported by laboratory experiments?

a. Cadherins and integrins are used for cell adhesion during the formation of temporary multicellular structures to defend against predators.

b. The genes are not actually expressed and are simply vestiges of an ancestor that used cadherins and integrins for adhesion.

c. Cadherins and integrins are used for cell adhesion during the formation of complex multicellular structures that are resistant to freezing temperatures.

d. Choanoflagellates use adhesion molecules to help capture bacterial prey.

e. Choanoflagellates are parasites and use cadherins to attach to host organisms.