The correct option is C Steel
Heterogeneous Mixture:
A heterogeneous mixture is composed of components that are not uniform and have different properties. Milk, soil, smoke are the heterogeneous mixture.
Homogeneous Mixture:
A homogeneous mixture is composed of components that are uniform with fixed composition and proportions
e.g. steel is an alloy of iron and carbon with fixed ratios.
Hence, option B is correct.