challenge: What is the composition of the vowel system in the Shehri language?
  
  A. A 4-member set consisting of only lax vowels
  B. An 8-member set containing i, e, Ó, Í, a, Ã, o, and u
  C. A 6-member set consisting of i, e, a, o, u, and Ã
  D. A 5-member set containing only tense vowels
  Answer: 