Yaties correction of continuity is

A. $${\chi ^2} = \frac{{N{{\left[ {\left( {ad - bc} \right) - \frac{1}{2}N} \right]}^2}}}{{\left( {a + c} \right)\left( {b + d} \right)\left( {a + b} \right)\left( {c + d} \right)}}$$

B. $${\chi ^2} = \frac{{\left( n \right)\left( {\sigma _s^2} \right)}}{{\sigma _0^2}}$$

C. $${\chi ^2} = \frac{{\sum {{\left( {{O_f} - {E_f}} \right)}^2}}}{{\sum f}}$$

D. None of the above

Answer: Option A