How do bolts as anchors compare to natural protection in terms of reliability and maintenance?

• A. Bolts always fail under load, whereas natural protection never does.
• B. Bolts provide predefined anchors with known pull tests when maintained; natural protection depends on rock features and can fail due to rock quality or movement; redundancy is essential for both.
• C. Natural protection is always more reliable than bolts; maintenance is unnecessary.
• D. Bolts and natural protection are identical in reliability; redundancy is optional.

Answer: (B)