The correct answer is B) machined metallic packing strips or fins. Labyrinth seals used to reduce leakage around a turbine shaft are constructed of machined metallic packing strips or fins. This design creates a tortuous path for the fluid flow, which helps to minimize leakage. Metallic materials are commonly used for labyrinth seals due to their durability and ability to withstand the high-speed rotational forces present in turbine applications. The other options are incorrect because: A) Spring bound carbon segments are not typically used for labyrinth seals. C) Staged rubber composition seal stripping is more commonly used for static seals, not rotating shaft applications. D) Braided asbestos covered core segments are not a modern construction material for labyrinth seals.