What marked the end of the Precambrian period? A. The appearance of complex, multicellular animals B. The division between archaea and eukarya C. The emergence of simple, protist-like animals D. The development of DNA-based viruses Mark for review (Will be highlighted on the review page)

A. The appearance of complex, multicellular animals

Explanation:

Precambrian period is the earliest period in the history of the earth. It was characterized by different evolutionary characteristics and differences.

The end of this period was marked with The appearance of complex, multicellular animals which were able to perform complex tasks

tissue

explanation:

it is actually formed by geoup of cells which is tissue

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.