The effect of the presence of impurities such as carbon and sulphur on iron is that they

Explanation: Pure iron is soft and quite malleable. When impurities such as carbon or sulphur are present:

• Carbon: strengthens the iron by restricting the movement of atoms, which increases the hardness and tensile strength.
• Sulphur: can make iron more brittle, but overall, impurities are what turn pure soft iron into stronger steels with higher tensile strength.

They do not make iron more malleable/ductile (B), and they do not raise or lower the melting point in a way that defines their main effect in metallurgy. The most recognized effect is the increase in tensile strength.