$$ \text { Consider the following molecules/species : } $$

$$ \text { The correct order of carbon-oxygen double bond length is : } $$

$$ \text { The following structures are } $$

$$ \text { The descending order of acidity among the following compounds is : } $$

Choose the correct answer from the options given below :

$$ \text { The strongest conjugate acid will result from : } $$