Final answer:
The 'basic' level of observation should be used to consider the three-dimensional form from all directions, focusing on volume and indentation.
Step-by-step explanation:
During the level of observation where you consider the three-dimensional form from all directions, determining where volume (mass or fullness) and indentation (hollowness) are positioned, you should engage in what is known as a basic level of observation (A). This fundamental approach is essential when analyzing sculptures, installations, and other three-dimensional works of art. It involves assessing the work's physical presence and spatial dimensions, encompassing its height, width, and length. Such an analysis can often reveal more about the piece, such as the use of geometric or organic shapes and how the artwork interacts with the space around it.