Which of the following tools lets you design multi-colored filled objects with maximum fluid color transitions in Corel Draw?

Hi. I've got a question on which people have split opinions. Some people say A), some B) and even C)

Which of the following tools lets you design multi-colored filled objects with maximum fluid color transitions in Corel Draw?
    A. Interactive Fill
    B. Smart Fill
    C. Mesh Fill
    D. Fountain Fill