Understanding the Concept of 'Abettor'

In CLAT UG 2020, question 37 stated: 'A, B and C are friends, living in a hostel. A is an excellent cook and often prepares food for them. One day while B was leaving the hostel, C put his tiffin box in the bus as C thought that it belonged to A. However, the tiffin box belonged to Z who is not a student of that hostel. Z had kept it in the hostel as he was planning to stay back for a day. When the bus moved, the tiffin box slipped from the seat and fell on B's leg, causing him injuries. A, the cook, was present and had seen the whole incident. A helped B in taking him to the hospital and later informed the hostel authorities about the incident, suggesting that the hostel staff should inform Z about the incident.