Final answer:
Vitor Becker's work primarily focuses on the organism level, which encompasses all the complex systems within a living being that allow it to function and maintain life.
Step-by-step explanation:
The main focus of Vitor Becker's work is at the organism level, which is the highest level of organization in biological hierarchies. An organism is a living being capable of performing all physiological functions necessary for life. In the context of multicellular organisms, like humans, this includes a complex system where cells, tissues, organs, and organ systems all work together to maintain the life and health of the organism.