Where $Nu =$ Nucleophile. Find out the correct statement from the options given below for the above $2$ reactions.

• A
  Reaction $(I)$ is of $2^{nd}$ order and reaction $(II)$ is of $1^{st}$ order
• B
  Reaction $(I)$ and $(II)$ both are of $2^{nd}$ order
• C
  Reaction $(I)$ is of $1^{st}$ order and reaction $(II)$ is of $2^{nd}$ order
• D
  Reactions $(I)$ and $(II)$ both are of $1^{st}$ order