Which flux is used in iron and steel while brazing?

A. Mixture of 70% borax powder with 30% boric acid

B. Mixture of 75% borax powder with 25% boric acid

C. Mixture of 80% borax powder with 20% boric acid

D. Mixture of 85% borax powder with 15% boric acid

Correct Answer: Mixture of 75% borax powder with 25% boric acid