Can someone please explain how that is the answer? The process step by step.

In what order does the guess function process the following tree's nodes? (What is the output?) 70 20 30 90 Algorithm guess(root) if (root) guess(root>right) guess(root->left) process(root->data) else print ("*") end if 11kI end guess 30 9070 20 90 3020 70 *90 30**20 70