In the Cannizzaro reaction given below:
`2Ph-CHO overset(overset(Θ)OH)rarrPh-CH_(2)OH+PhCO_(2)^(-)` the slowest step is:
A. the attack of `OH^(-)` at the carbonyl group
B. the transfer of hydride to the carbonyl group
C. the abstraction of proto from the the carboxylic acid
D. the deprotonation of `Ph-CH_(2)OH`
