Which type of flower arrangement is characterized by having multiple flowers on a single stick?

The correct answer is that line flowers are characterized by having multiple flowers on a single stem. Line flowers are typically long, linear, and create a structural framework for the arrangement. This type of flower arrangement contributes height and form, guiding the eye along a specific path through the design. The individual flowers are often spaced along a single stem, which helps to accentuate their verticality and elegance.

Mass flowers, on the other hand, are used for their dense blooms and are typically arranged to create volume and color within a floral display. Filler flowers serve to add texture and fill in gaps within an arrangement but do not have the same structural qualities. Compound flowers, while they may feature multiple blooms, do not specifically describe the arrangement style defined by a single stem with multiple flowers.

Thus, line flowers uniquely fit the description of having multiple flowers on a single stick, making them the correct choice for this question.