Both A and B went to the field to protect the crop from being reaped forcibly by an opposite party, and in the course of that, A killed a person.

Correct option is B

1. Murder Liability: As per criminal law, liability for murder is based on actus reus (the act) and mens rea (the intent). Merely accompanying someone to a location does not automatically make a person complicit in a crime unless there is evidence of a common intention (under Section 34 of IPC or under Section 3(5) in Bharatiya Nyaya Sanhita, 2023).
2. In this scenario, A committed the act of killing, making A directly responsible for the act of murder.
3. B's presence alone does not establish that B shared the intent or participated in the act. Without evidence of a shared common intention to kill, B cannot be held liable for the murder.