Final answer:
Barge rafters are typically one size narrower than common rafters. Size is the correct choice from the given options.
Step-by-step explanation:
When compared to common rafters, barge rafters are typically one size narrower. The correct answer is b. Size. In construction, rafters support the roof of a building and the term 'barge rafter' refers specifically to the rafter that follows the slope of the gable end of a building. When constructing a roof, it is standard practice for barge rafters to be slightly narrower than common rafters because they do not need to carry as much load as the ones supporting the main span of the roof. As a result, for consistency and to follow construction standards, it is important to keep this sizing difference in mind.