Compare the two methods shown for the preparation of carboxylic acids.
Method $1$: $RBr$ $\xrightarrow[diethyl \ ether]{Mg} RMgBr$ $\xrightarrow[2. \ H_3O^{+}]{1. \ CO_2} RCO_2H$
Method $2$: $RBr$ $\xrightarrow{NaCN} RCN$ $\xrightarrow[heat]{H_2O, HCl} RCO_2H$
Which one of the following statements correctly describes this conversion for the given substrate ($1$-bromoadamantane)?

• A
  Both Method $1$ and Method $2$ are appropriate for carrying out this conversion.
• B
  Neither Method $1$ nor Method $2$ is appropriate for carrying out this conversion.
• C
  Method $1$ will work well,but Method $2$ is not appropriate.
• D
  Method $2$ will work well,but Method $1$ is not appropriate.