The increasing order of the rate of `HCN` addition of compound a-d is
(i) `HCHO`
(ii) `CH_(3)COCH_(3)`
(iii) `PhCOCH_(3)`
(iv) `PhCOPh`

Options

A. `iv lt ii lt iii lt i`
B. `iv lt iii lt ii lt i`
C. `iii lt iv lt ii lt i`
D. `ilt ii lt iii lt iv`.

Answer

B