JEE Main Chemistry question

The self ionisation constant for pure formic acid, K=[HCOOH₂⁺][HCOO⁻], has been estimated as 10⁻⁶ at 1.22 g/cm³. The percentage of formic acid molecules in pure formic acid converted to formate ion is:

• (A)0.002%
• (B)0.004%Correct
• (C)0.006%
• (D)0.008%