What is primarily evaluated by actuaries in the context of insurance operations?

Actuaries primarily focus on the ultimate value of losses and Incurred But Not Reported (IBNR) reserves because their role involves analyzing data to assess financial risks associated with insurance. This includes estimating the future costs of claims that have occurred but have yet to be reported, which is critical for setting appropriate reserves.

By evaluating the ultimate value of losses, actuaries help ensure that enough funds are reserved to cover future claims, maintaining the insurer's solvency and stability. This assessment involves complex statistical models and an understanding of various risk factors, claims patterns, and loss development trends. Thus, the calculation and management of IBNR reserves are fundamental for financial planning and regulatory compliance within insurance operations.

The other options, while relevant to insurance operations, do not encapsulate the primary responsibility of actuaries. For instance, analyzing the average claims paid out and the total number of claims filed focuses more on operational metrics rather than the financial forecasting and risk assessment that actuaries perform. Marketing effectiveness, on the other hand, falls outside the scope of actuarial analysis, aligning more with sales and marketing departments. Therefore, the correct choice highlights the critical role actuaries play in the financial health and risk management of insurance companies.