Right option is (b) Magnesium chloride
To explain I would say: Reaction 2C2H5 MgCl+2C2H5 Cl+Pb →Pb(C2H5)4 + 2MgCl2 is involved in the production of tetra ethyl lead. Hence the raw materials required are lead metal, ethyl chloride, and ethyl magnesium chloride.