Question

what additional characteristic (x) belongs in the central section of the venn diagram? ribosome mitochondrion chloroplast endoplasmic reticulum

Explanation:

Ribosomes are found in both prokaryotic and eukaryotic cells. Mitochondria, chloroplasts, and endoplasmic reticulum are only present in eukaryotic cells. Since the Venn diagram likely represents common features between two cell types (possibly prokaryotic and eukaryotic), ribosome is the correct choice.

Answer:

A. Ribosome