What is the minimum height of a bank above the surface of the green?

The minimum height of a bank above the surface of the green is established to ensure fair play and safety in the game of bowls. A bank that is 230 mm high provides sufficient elevation to prevent bowls from rolling off the green while also contributing to the overall design and functionality of the bowling area. This height is established through guidelines that balance the practical aspects of play, such as ease of bowl retrieval and visibility for players, with the need to maintain the integrity of the game. The specified height helps in maintaining consistency across bowling greens, ultimately contributing to a uniform playing experience.

In contrast, options that suggest lower heights do not meet the necessary requirements for effective play, as they may allow bowls to roll off the green more readily, undermining the rules and flow of the game. Thus, the choice of 230 mm reflects a well-considered standard that supports the objectives of the sport.