A nurse is collecting data from a child who is descending stairs by placing both feet on each step and holding on to the railing. The nurse should understand that these actions are developmentally appropriate at which of the following ages?

The correct answer is A: 3 years. At around 3 years old, children typically start descending stairs by placing both feet on each step and holding onto the railing for support. This is developmentally appropriate as it shows they have developed the coordination and balance to navigate stairs safely. At 6 years old (choice B), children should already be able to descend stairs without needing to place both feet on each step. Choices C (5 years) and D (4 years) are also incorrect as children at these ages should be displaying more advanced stair-descending skills compared to placing both feet on each step.