The word Montana has a total of 7 letters this number becomes our denominator because this is the total amount of letters. Three of the letters contain vowels, this number will go on top. These letters include o, and two a (s).
This will give us the answer of 3/7. This fraction cannot be reduced any further.
The answer should result in b.
It appears the slash was forgotten to be written in the answer, try not to make this mistake on any tests!
Hope this helped! :)