What structural component is used to support floors and ceilings between two walls?

The correct choice is joists, as they play a critical role in supporting floors and ceilings. Joists are horizontal structural members that span the space between walls or beams, providing the necessary support for the weight of flooring above or ceilings below. They are typically made of wood or engineered wood products and are strategically placed to distribute loads evenly, ensuring stability and structural integrity.

In contrast, beams serve as the primary horizontal support in larger structures and often carry significant loads from the joists or other structural elements. Pillars are vertical supports used to bear loads and may be essential in certain designs, but they are not specifically designed to support floors and ceilings between walls. Studs are vertical framing members used in walls and are not responsible for supporting floors or ceilings; instead, they help create the wall structure itself. Thus, the role of joists as the key component for this function makes them the correct answer.