I have the following question in one of my exercises and hope you can help me with it.

" Sarah is the leader of the Great Party. During a political rally, she made certain untrue and slanderous allegations about Mr John, who is the leader of another political party. These allegations where made in her capacity as leader of the Great Party. Mr John wants to institute a defamation action, but he is unsure whether he should sue the Great Party or Ms Sarah in her personal capacity. Advise him"