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

[EX Q]: Climatic regions Contrasts between the interior and the coasts produce _ main climatic regions.
[EX A]: six

[EX Q]: Vitamins are classified into _ groups.
[EX A]: two

[EX Q]: Water is the only substance on earth that exists naturally in _ states .
[EX A]:
three