Eschka mixture, which is used for the determination of sulphur in coal, is a mixture of _____________________?

Eschka mixture, which is used for the determination of sulphur in coal, is a mixture of _____________________?

A. MgO & Na2CO3
B. MgSO4 & BaCl2
C. BaSO4 & NaCl
D. MgCO3 & NaCl