What is the minimum size for a manhole opening?

The correct answer is that both options B and C are acceptable as minimum sizes for a manhole opening.

In engineering and construction practices, manholes serve an essential function for access to underground utilities, allowing for maintenance and inspection. Standard dimensions for manhole openings ensure both functionality and safety. A manhole opening that is at least 10 inches by 16 inches (as stated in option B) provides adequate space for personnel to enter and exit safely while performing their tasks. Similarly, the dimensions of 11 inches by 15 inches (as stated in option C) also meet the necessary requirements for safe access.

By acknowledging that both B and C meet the minimum size requirements, the answer reflects an understanding of standard engineering practices regarding utility access points. This ensures that maintenance workers can efficiently and safely operate within manholes, regardless of which of the two sizes is used.