What defines a lobe in the context of body organs?

A lobe in the context of body organs is defined as a division marked off by a fissure on the organ's surface. This anatomical feature is commonly observed in various organs, such as the lungs and the liver. In the lungs, there are distinct lobes separated by fissures that help to categorize the lung tissue based on functionality and organization. Similarly, in the liver, the structure is divided into lobes that contribute to the overall function of the organ.

The other choices describe characteristics or functions that are not specific to the definition of lobes. While areas that contain multiple cell types may exist within lobes, the presence of diverse cell types does not inherently define what a lobe is. Hormonal regulation is a function of certain structures in the body, but it does not pertain to the structural definition of a lobe. Likewise, fluid storage can be a function of certain organs, but again, this does not relate to the anatomical identification of lobes. Thus, the correct definition directly reflects how these divisions are visually and structurally identified on organs.