This question is about maintaining a consistent point of view across a list of instructions joined into one sentence. When a sentence lists several pieces of advice, every item should stay in the same person and voice unless there is a clear reason to shift.
Reading the whole sentence together: "In a conflict, speak in a pleasant way, send appropriate non-verbal messages to the other person, and match your non-verbal behaviour to the spoken message." Phrases (a), (b) and (d) stay in a consistent, generalised instructional tone, while (c) alone breaks that consistency by switching to the personal "your", making it the odd phrase out.
Let's summarize:
The correct answer is option 3, phrase (c).