Which of the following are the 6 types of underground distribution systems?

The selection of B as the correct answer is due to its accurate identification of the six recognized types of underground distribution systems utilized in electrical engineering and infrastructure. These systems include Radial, Loop Radial, Primary Loop, Dual Radial, Network Systems, and 600v Primary Systems.

Radial systems are often the simplest configuration, providing power from a single source to multiple loads, while Loop Radial systems allow for some redundancy and enhanced reliability by allowing power to flow in multiple directions. Primary Loop systems can improve efficiency and reduce line losses by allowing load balancing and alternate feed options. Dual Radial systems provide a higher level of reliability and are designed to supply power through more than one position. Network Systems offer even greater reliability and resilience, especially in urban settings where demand is high, allowing for multiple feed points. The reference to 600v Primary Systems is also accurate, representing a common voltage level for primary distribution.

This comprehensive representation of underground distribution systems is critical for understanding how electrical power is effectively managed and delivered in various settings, ensuring reliability and efficiency. Other options do not correctly list all six types or include inaccuracies in the mentioned systems and their classifications.