Which guideline is correct regarding notching and boring of joists?

When considering the correct guideline for notching and boring of joists, the emphasis on boring at least 2 inches from the edges is crucial to maintaining the structural integrity of the joist. This guideline ensures that there is sufficient material left around the bore to support loads without compromising the joist's strength. Boring too close to the edges can weaken the joist, leading to potential failure under loads, making it essential to adhere to this distance to enhance safety and reliability in construction.

The other options, while they may include valid points about notching and boring practices, do not emphasize the critical aspect of avoiding structural weakness as effectively as the correct choice does. Maintaining proper spacing from the edges is a key factor in preventing structural issues, making this guideline particularly important for builders and contractors to follow.