5. A perceptual region's boundaries are a. Determined by a set of uniform physical and cultural characteristics across a particular area.
b. Drawn around the functions that occur between a particular place and the surrounding area.
c. Determined by the portion of a particular area that has been modified by human activities.
d. Fuzzy because they allow for individual interpretation.
e. Designated by the inclusion of a particular cultural characteristic.

d. Fuzzy because they allow for individual interpretation.

Explanation:

In Geography, a region can be defined as an area physically set apart by definable characteristics or attributes from others.

Basically, regions are part of planet earth and are typically characterized by similarities based on features such as culture, religion, political systems, language, etc. Thus, a region is characterized by political and human features.

Additionally, regions are generally studied with respect to place, space and location. There are mainly three types of regions;

I. Formal (uniform) region.

II. Functional (normal) region.

III. Perceptual (vernacular) region.

A perceptual region is centered on prejudices, feelings, or emotions which are subjective because they may be true or false. Thus, it's a type of region that is typically based on an individual's mental map or perception and as such may not reflect the true nature.

This ultimately implies that, perceptual or vernacular regions are defined by commonly perceived characteristics of different individuals about specific places on planet earth. An example is the slums of Detroit.

Hence, a perceptual region's boundaries are fuzzy because they allow for individual interpretation.