Question: You want to implement the behavior of an effect like `slideDown()` manually using `animate()`. What is one critical point you need to remember?

1. `slideDown()` requires animating the background color; doing so with `animate()` requires the jQuery Color plugin.
2. `slideDown()` includes toggling visibility automatically. `animate()` does not automatically set any properties.
3. `slideDown()` requires the element to have a height set in pixels. `animate()` does not.
4. Effects created with `animate()` must be run over at least 100 milliseconds, where `slideDown()` can run as quickly as 50ms.

Answer: The correct answer of the above question is Option B:`slideDown()` includes toggling visibility automatically. `animate()` does not automatically set any properties.