Titration is carried out for 3 moles of a mixture of ferrous and ferric sulphate, which required 100 ml of 2 M potassium

Hi, I have a question and I hope anyone could answer it:

Titration is carried out for 3 moles of a mixture of ferrous and ferric sulphate, which required 100 ml of 2 M potassium permanganate in acidic medium. Hence the mole fraction of ferrous sulphate in the mixture is ______ .

(a) 1/3 

(b) 2/3 

(c) 2/5 

(d) 3/5