The correct answer is: b) Scavenging system.
Scavenging is a traditional practice of pig rearing in Nagaland. In this system, pigs are allowed to roam freely and forage for their own food. This system is sustainable and low-cost, but it can be difficult to control the health and welfare of the pigs.
Intensive pig farming is a more modern practice in which pigs are kept in confined spaces and fed a diet of commercial feed. This system is more efficient in terms of production, but it can be stressful for the pigs and can lead to health problems.
Penning is a system in which pigs are kept in pens with access to outdoor areas. This system is a compromise between scavenging and intensive pig farming, and it can provide a good balance of welfare and production.
Stall feeding is a system in which pigs are kept in stalls and fed a diet of commercial feed. This system is the most efficient in terms of production, but it can be stressful for the pigs and can lead to health problems.
In conclusion, the traditional practice of pig rearing in Nagaland is scavenging. This system is sustainable and low-cost, but it can be difficult to control the health and welfare of the pigs.