Explanation:

One possible way to insert the code boxes in the correct positions in order to build a line of code which asks the user for an integer value and assigns it to the depth variable is:
depth = int(input("Enter the immersion depth: "))
This line of code uses the input function to prompt the user for a string value, and then uses the int function to convert that string value into an integer number. The result is then assigned to the variable depth.
You can find more information about the input and int functions in Python in the following references:
* [Python input() Function]
* [Python int() Function]