Where does undigested food and reproductive cells come out of the aurelia?

Undigested food  will be diffused from the surface of skin and reproductive cells come out of the mouth in aurelia.

Explanation:

The gastro vascular system in aurelia helps remove carbon dioxide and waste material from aurelia as there is no specialised excretory system. The waste material is diffused out through general body surface.

Aurelia are dioceous which means sexes are separate. Four gonads of either sex lie radially on the floor of gastric pouches. The gametes when ripened gets shed in the stomach from gonads and comes out of the mouth.

The spermatozoa shed by the mouth in seawater gets carried to the body of female by mouth. The fertilization takes place in gastric pouches.

the answer to your question is:

c. complementary base-pairing

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs