Which option describes a SAE Grade 5 bolt?

A SAE Grade 5 bolt is marked with 3 radial lines. This marking indicates that the bolt has been manufactured to specific mechanical properties that provide medium tensile strength. The presence of the three radial lines is crucial for identification and ensures that users can easily recognize the bolt's grade and strength characteristics. In the context of fasteners, this grading system is vital for ensuring that the right bolt is used in applications where specific load-bearing capacities are critical.

While other options describe different markings or lack of markings, only the correct identification with three radial lines corresponds to the recognized standards for a Grade 5 bolt, providing assurance regarding its material performance in various mechanical applications.