Consider the following Cannizzaro reaction
`2Ph-CHOoverset(OH^(-))rarrPh-CH_(2)OH+PhCO_(2)^(-)`
In the above reaction, the slowest step of the reaction is
A. the attack of `-OH` at the carbonyl group
B. the transfer of hydride ion to the carbonyl group
C. the abstraction of proton from the carboxylic acid
D. the deprotonation of `Ph-CH_(2)OH`.