Final answer:
The balusters of a deck less than 30 inches off the ground must have no more than 4 inches between them to ensure safety.
Step-by-step explanation:
The subject of this question is Construction. Specifically, it pertains to the construction of a deck and the requirements for the balusters.
According to the building codes, if a deck is less than 30 inches off the ground, the balusters (also known as spindles or pickets) must have no more than 4 inches between them.
This requirement ensures the safety of the deck by preventing small children and pets from getting through the gaps between the balusters.