What is a key characteristic of trigger flowers?

Trigger flowers are known for their ability to catch the eye and emphasize the overall design of a floral arrangement. They often have vibrant colors or unique shapes that make them stand out, functioning as focal points that draw attention. Their role in an arrangement is crucial as they can highlight other flowers and elements while helping to create a balanced composition.

In contrast, while trigger flowers can be large and colorful, this isn't their defining characteristic compared to their specific role in arrangement (thus not the correct choice). Although they can sometimes dominate a design, this is not their primary function. Likewise, while they may serve to complement other flowers, their main purpose is not to provide a background as that would typically be the role of foliage or more subtle blooms. Therefore, recognizing that trigger flowers focus attention and enhance visual interest is what makes the selected answer accurate.