One purpose of a load moment indicator is to:

A load moment indicator (LMI) plays a critical role in crane safety by continuously monitoring the load being lifted in relation to the crane's capacity. Its primary purpose is to warn the operator of an overload condition. When the load approaches or exceeds the crane's rated capacity, the LMI provides alerts to the operator, helping to prevent accidents and maintain safe operation. This is vital because exceeding the load limit can lead to crane instability and potential tipping, which poses significant risks to both personnel and equipment.

While other aspects, such as load distribution and operational efficiency, are important in crane operations, the LMI’s foremost function is risk mitigation through overload warnings. This is why option C is the correct answer.