Final answer:
The bending radius "R" of reverse curves in lead-covered cables must be a particular multiple of the cable's overall diameter based on engineering guidelines and electrical code requirements. However, the exact factor needs a reference to specific standards or specifications.
Step-by-step explanation:
In general, the bending radius "R" of the reverse curves in lead-covered cables should be no less than certain times the overall diameter of the cable. For a typical cable installation, engineering guidelines recommend that this radius be sufficiently large to prevent damage to the cable while ensuring safety and adherence to electrical code requirements. In this scenario, without the specific guidelines or code references, we cannot provide the exact minimum bending radius requirement. The options given (5, 8, 10, 12 times the overall diameter) likely refer to a standard, but the exact number can vary based on the type of cable and manufacturer specifications. Therefore, if provided an engineering standard or electrical code, the bending radius can be determined accordingly.