Anchor bolts must be embedded in concrete or reinforced masonry at least:

The correct choice is based on the California building codes, which specify the minimum requirements for the embedment of anchor bolts in concrete or reinforced masonry. The standard for most common applications—including anchoring for wood and metal structures—requires that anchor bolts have a minimum embedment depth of 7 inches. This depth ensures adequate load distribution and resistance to pull-out forces, contributing to the overall structural integrity of the construction.

This requirement is essential for providing a secure attachment of structural elements like columns, walls, and foundations, ensuring that the anchoring system can withstand lateral and vertical loads. When anchor bolts are not installed to the required depth, it diminishes their effectiveness, potentially compromising the structure's stability and safety.

In contrast, other values provided in the choices do not meet the established minimum embedment requirements outlined in the building codes, emphasizing the importance of adhering to the specified standards to avoid structural failures.