Final answer:
The time complexity for visiting all nn nodes in a binary tree is Θ(n).
Step-by-step explanation:
The time complexity for visiting all nn nodes in a binary tree depends on the number of nodes and the structure of the tree. In the worst case scenario, we need to visit each node once, resulting in a time complexity of Θ(n). This means that the time required to visit all nodes grows linearly with the number of nodes in the tree.