Correct option is D
Calcium and sodium lubricants are classified as
semi-solid lubricants, typically in the form of
greases. They are created by combining calcium or sodium-based soaps with a lubricating oil to produce a grease-like consistency. These semi-solid lubricants are widely used in applications where a long-lasting and thick lubricant is required to stay in place and provide lubrication under moderate loads and speeds.
