Which of the below reactions produce carboxylic acids?

(a)  $\frac{{\mathrm{MnO}}_2}{{\mathrm{CH}}_3{\mathrm{COCH}}_3}$

(b) $\mathrm{Ph}-{\mathrm{CCl}}_3\frac{\text{ (i) aq.NaOH }}{\text{ (ii) }{\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{\oplus }}$

(c) ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br}{\frac{\left(\mathrm{i}\right)\mathrm{Mg}}{\left(\mathrm{ii}\right){\mathrm{CO}}_2}}_{\left(\mathrm{iii}\right){\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{\oplus }}$

(d) ${\mathrm{CH}}_3\mathrm{CH}={\mathrm{CHCH}}_3\frac{{\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7/{\mathrm{H}}_2{\mathrm{SO}}_4}{\Delta }$

(b) $\mathrm{Ph}-{\mathrm{CCl}}_3\underset{\left(\mathrm{ii}\right){\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{+}}{\overset{\left(\mathrm{i}\right)\mathrm{aq}.\mathrm{NaOH}}{\to }}\mathrm{Ph}-\mathrm{C}(\mathrm{OH}{)}_3\underset{-{\mathrm{H}}_2\mathrm{O}}{\overset{{\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{+}}{\to }}\mathrm{PhCOOH}$

(c) Alkyl halide when reacts with magnesium metal, it forms grignard reagent which on reaction with dry ice forms carboxylic acid.

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br} + \mathrm{Mg}\stackrel{}{\to }{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{MgBr}\underset{{\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{+}}{\overset{{\mathrm{CO}}_2}{\to }}{\mathrm{CH}}_3\mathrm{COOH}$

(d) Alkenes on oxidation with acidified dichromate forms carboxylic acid depending upon nature of alkene.

Here, $=\mathrm{CH}$ is oxidised to $-\mathrm{COOH}$ as:

${\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_3\underset{∆}{\overset{{\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7/{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}2{\mathrm{CH}}_3\mathrm{COOH}$