The study of which structure was instrumental in the formulation of the modern cell theory?

In the item, we are asked to identify the study of which structure was instrumental in preparation for the formulation of modern cell theory. The scientific study is named DNA molecules. Modern cell theory has given rise to many scientific advances especially in medication.

Study of DNA was most instrumental in formulation of the modern cell theoy, which states that cell are capable of reproduction, and function, and heredity, along with being a structure. It also stated that some organisms are made up of more than one cell.

The answer should be a