Final answer:
The correct answer to fill in the blanks for the given sentences '[ A _ _ _ B ] ... There are exactly three spaces between A and B / A and B are within three spaces.' is option a) 'Between; within', which accurately describes the spatial relationship between A and B.
Step-by-step explanation:
The question relates to word choice in phrasing a sentence correctly. In sentence construction, the words that join other words or concepts are crucial. In the given problem, we are looking to correctly fill the blanks in the sentence '[ A _ _ _ B ] ... There are exactly three spaces between A and B / A and B are within three spaces.'
Option a) which states, 'Between; within' correctly completes the sentence. Here's why: 'Between' indicates the position in the middle of two points (in this case A and B) and 'within' indicates something is inside or not further than an area or period. Neither 'surrounding' nor 'beyond' would suit the context as they imply being all around something or being past a certain limit, respectively.