The correct answer is option D - Transport organic materials in and out of the cells, but more specifically, to modify, sort, and package proteins and lipids for transport out of the cell.

The Golgi complex, also known as the Golgi apparatus, is a complex organelle found in eukaryotic cells. Its main functions include:

- Modifying proteins and lipids (e.g., glycosylation, phosphorylation)

- Sorting and packaging proteins and lipids for transport

- Transporting materials to lysosomes, plasma membrane, or other organelles

The other options are not accurate:

A. Conducting ions in and out of the cell is the role of ion channels and pumps, not the Golgi complex.

B. Transporting genetic materials out of the cell is not a function of the Golgi complex.

C. Providing attachment for ribosomal granules is the role of the endoplasmic reticulum (ER), not the Golgi complex.