The correct option is
C A>D>C>BAfter the loss of proton, conjugate bases formed are :
![](https://search-static.byjusweb.com/question-images/byjus/ckeditor_assets/pictures/1014231/original_1533.JPG)
Since, on losing
H+, structure A and D become neutral, so they are more stable than B and C
Between B and C :
Negative charge on more electronegative atom (oxygen) is more stable, as in structure C than less electronegative atom (nitrogen) as in structure B.
So, C is more stable than B.
Between A and D :
More the electronegativity, more is the stability of conjugate base.
Since electronegativity of oxygen is more than that of nitrogen
So, A is more stable than D
Overall order of stability of conjugate base :
A>D>C>B Stability of conjugate base∝Acidic strength Acidic strength order :
A>D>C>B