Final answer:
The phrase 'to space out' refers to a mental state where an individual loses focus or awareness, and is not related to astronomy, technology, or construction.
Step-by-step explanation:
The phrase 'to space out' as a verb phrase describes the mental state (A) wherein a person temporarily loses focus or becomes unaware of their surroundings. Often, the term conveys a sense of being lost in thought or daydreaming where the person's attention is not present in the immediate situation. This is different from astronomical events, technological advancements, or construction methods, which the other options B, C, and D might suggest.