Which label belongs in the area marked X?

nucleus
DNA
cell wall
ribosomes

"griffith's experiment discovering the "transforming principle" in pneumococcus bacteria. griffith's experiment, reported in 1928 by frederick griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation." - griffith's experiment.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.