Organic pigments are generally described as:

Organic pigments are indeed generally characterized by being brighter in color but less resistant to heat compared to their inorganic counterparts. Organic pigments typically offer a broader range of vivid colors, making them desirable for applications that require striking aesthetics. However, they tend to have lower thermal stability, meaning they can degrade or change color when exposed to high temperatures. This characteristic is crucial for painters and contractors to consider when selecting pigments for various environments or applications, as it impacts the longevity and durability of the paint finish.

The emphasis on brightness and heat sensitivity helps distinguish organic pigments from inorganic ones, which usually exhibit more muted colors and better heat and light stability. When choosing paint formulations, understanding these properties can significantly influence the overall performance and appearance of the finished work. Thus, option B accurately captures a defining feature of organic pigments in comparison to other types.