ANS:B - tungsten, chromium & vanadium.

In 18-4-1 high-speed steel, the numbers 18, 4, and 1 respectively denote the percentage of tungsten, chromium, and vanadium. High-speed steel (HSS) is an alloy steel commonly used in cutting tools, such as drills, taps, and milling cutters, due to its ability to maintain cutting performance at high temperatures. The numbers in the designation represent the approximate percentages of specific alloying elements in the steel composition. Therefore, in 18-4-1 high-speed steel:

• 18 indicates the approximate percentage of tungsten.
• 4 indicates the approximate percentage of chromium.
• 1 indicates the approximate percentage of vanadium.