Answer:
The correct option is nucleus.
Explanation:
When observations of an onion cell are made through a compound microscope in a lab, the onion cells are strained so that the nucleus becomes visible. The onion cells are strained with iodine solution so that the nucleus of the onion cells can also become visible under the compound microscope.
The nucleus is the site where the genetic material is present. For multicellular organisms, the DNA will be packed and present in the chromosomes.
