According to ASTM specifications, all exposed ends of tubular posts should be fitted with caps of:

• A. Aluminum alloy
• B. Formed steel
• C. Malleable or cast iron
• D. All of the above

Answer: (D)

Protecting the ends of tubular posts is required to seal the end, keep out moisture and debris, prevent corrosion, and reduce injury. ASTM specifications permit a range of cap materials as suitable for end caps, as long as they fit the post and environment. The listed materials—aluminum alloy, formed steel, and malleable or cast iron—are all acceptable options. Because the standard focuses on end protection rather than restricting to a single material, all of the above can be used to cap exposed ends. The best choice depends on compatibility with the post and conditions, but the essential point is that ends must be capped.