In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Example Input: Pelagic division is divided into neritic and _ levels of pelagic provinces.
Example Output: three

Example Input: White sturgeon inhabit _ large river systems, all on the western coast of North America.
Example Output: three

Example Input: Spheres describe systems with _ levels of equal degeneracy.
Example Output:
two