The best-case height of a binary tree with seven nodes is 2. This is because, in the best-case scenario, the binary tree would be balanced, with each node having exactly two children. This means that the tree would have a shape similar to a full binary tree, where all levels of the tree are completely filled except possibly the last level, which is filled from left to right.
With seven nodes, the binary tree would have three levels, with the root node at the top level, three nodes at the second level, and three leaf nodes at the third level. The height of the tree would be the number of edges in the longest path from the root to a leaf, which in this case would be 2 edges.
Therefore, the best-case height of a binary tree with seven nodes is 2.