First, a complete digestive system means that the digestive tract has a beginning or the oral end and the opposite end or the aboral end. This is found in more complex animals starting from roundworms (flatworms have an incomplete digestive tract). A closed circulatory system is found in animals more recent than mollusks. The presence of the coelom makes it more evolved than the flatworms.
Specifically, a small animal with a segmented body, short stiff appendages, and soft skin with the above characteristics point out to the phylum Annelida or annelids.
Intetrference Competition: Competition that happens between two animals when someone interferes with someone else's foraging essentially.
1. Food web
2. Autotroph
3. Heterotroph
3. Decomposers
All ecosystems contain biotic and abiotic parts, so answer d.
