Which object not less than 10 centimeters in diameter can be considered as a monument?

• A. Wooden stake
• B. Stone pebble
• C. Concrete post
• D. Metal rod

Answer: (C)

Monuments in surveying and mapping are fixed, durable markers used to establish and preserve precise ground positions. They must be easy to locate, resistant to weathering, and of a size that distinguishes them from natural features—hence a minimum diameter of about 10 cm. Among the options, a concrete post best satisfies this: it is typically embedded in the ground as a sturdy, cylindrical marker with a diameter well over 10 cm, making it a reliable control monument. Wooden stakes degrade, stone pebbles are often too small or movable, and metal rods are commonly thinner and not as robust in field conditions.