The correct answer is "BIENTO" because if we look closely at the given words, we can see that there is a pattern in the spacing of the gap between the letters. In "REOSTRA", there is a gap of 1 letter between each letter. In "BOLADA", there is a gap of 2 letters between each letter. Therefore, following the pattern, in "BIENTO" there should be a gap of 3 letters between each letter.