a) decreases strength and hardness of steel
b) improves corrosion resistance
c) decreases ductility
d) improves strength and hardness of steel

Answer: d
Explanation: Manganese is added to improve strength and hardness of steel . Based on Manganese content, steel are classified as Carbon Manganese steel (Mn >1%) and Carbon Steel (Mn <1%). If its content exceeds 1.5%, it increases the formation of martensite and hence decreases ductility and toughness.