ANS:A - Bessemer steel

Right Answer is A: Bessemer Steel.

Explanation:
A) Bessemer steel.
B) Mild steel (Carbon 0.05-0.25%),
C) Cast steel (Carbon 0.1-0.5%).
D) Stainless steel (chromium 18 & Nickel 8%).

Mild steel = low carbon steel, Medium carbon steel (0.29-0.54%).,
High Carbon steel (0.55-0.95%) , Very High carbon steel (0.96-2%).
So rail steel High carbon steel used along with manganese.

Composition of rail steel: Carbon (0.82%,) and manganese( 1.7%) that it contains.Manganese steel is used at locations of the curve and, points and crossings.
But the whole rail is made of Bessemer steel. Hope you know the meaning of rail.