Which two numbers should be interchanged to make the given equation correct?

9 + 4 ÷ 2 – 6 × 3  =  4 ÷ 3 × 6 – 9 + 1       

6 and 4

9 + 4 ÷ 2 – 6 × 3  =  4 ÷ 3 × 6 – 9 × 1

⇒ 9 + 6 ÷ 2 – 4 × 3  =  6 ÷ 3 × 4 – 9 × 1

⇒ 9 + 3 – 4 × 3  =  2 × 4 – 9 + 1

⇒ 12 – 12  =  8 – 9 + 1

    0   =    0

L.H.S.   =  R.H.S.

So, option (C) is correct answer.