1-chlorobutane and 1-iodobutane each undergo reaction with aqueous sodium hydroxide via a nucleophilic substitution mechanism. Under identical conditions, which reaction has the highest rate, and which mechanism is used in this reaction?
- Agreatest rate: 1-chlorobutane; mechanism: $S_\text{N}1$
- Bgreatest rate: 1-chlorobutane; mechanism: $S_\text{N}2$
- Cgreatest rate: 1-iodobutane; mechanism: $S_\text{N}1$
- Dgreatest rate: 1-iodobutane; mechanism: $S_\text{N}2$