Consider the acidity of the carboxylic acids :
(a) `PhCOOH`
(b) `o-NO_(2)C_(6)H_(4)COOH`
(c) `p-NO_(2)C_(6)H_(4)COOH`
(d) `m-NO_(2)C_(6)H_(4)COOH`
Which of the following order is correct ?
A. `a gt b gt c gt d`
B. `b gt c gt d gt a`
C. `b gt d gt a gt c`
D. `b gt d gt c gt a`