Answer:
Option C, Single celled organisms and soft, boneless animals
Explanation:
The Precambrian era refers to the first geologic time frame and thus it refers to time frame which is some billion years old. During Archean period of Precambrian era, single celled /unicellular and simple form of organisms originated such as protozoans (including amoeba, euglena, and paramecium). These organisms developed with time and by the late Precambrian era soft bodied multi-cellular organisms like jellyfish, worms . moss etc. originated.
