The increasing order of the rate of HCN addition to compounds A – D is
(A) HCHO
(B) CH₃COCH₃
(C) PhCOCH₃
(D) PhCOPh

The correct order of increasing acid strength of the compounds

Reaction of cyclohexanone with dimethylamine in the presence of catalytic amount of an acid forms a compound if water during the reaction is continuously removed. The compound formed is generally known as

$$p$$-cresol reacts with chloroform in alkaline medium to give the compound A which adds hydrogen cyanide to form, the compound $$B.$$ The latter on acidic hydrolysis gives chiral carboxylic acid. The structure of the carboxylic acid is :