Final answer:
Lithium/barium base greases are ideal for high-temperature and high-speed applications with good water resistance, making them the best option among the choices listed.
Step-by-step explanation:
The most suitable semi-solid lubricant for use with high temperatures and high-speed ball and roller bearings that is also water-resistant is D) Lithium/barium base greases. Lithium and barium base greases are known for their good thermal stability, high dropping points, and effective sealing properties against water, making them excellent for extreme conditions found in high-speed bearings and automotive applications.
In contrast, aluminium base greases can work at high temperatures but might not be as water-resistant. Sodium base greases are not suitable for high temperature applications as they tend to wash out in the presence of water. Similarly, calcium base greases have good water resistance but lower temperature tolerance compared to lithium or barium base greases.