Which factor cannot be directly influenced by an insurance company?

Reinsurance is the correct choice because it is a transfer of risk between insurance companies and is typically dependent on external market factors and the terms agreed upon in reinsurance treaties. While an insurance company can negotiate reinsurance agreements and choose how much risk to cede, the availability, pricing, and conditions in the reinsurance market are influenced by broader trends, including economic conditions, regulatory changes, and the overall balance of risk across the insurance industry. Thus, while insurers can influence their strategy around reinsurance, they do not have direct control over the market itself or its terms.

On the other hand, the other factors listed can be directly influenced by an insurance company. Risk appetite reflects the company's willingness to take on risk and can be adjusted based on strategic priorities. Loss experience is a direct consequence of the claims that a company pays out, which can be managed by improving underwriting practices or implementing loss control measures. Underwriting parameters are the specific criteria that the insurer sets for evaluating risks, and companies can adjust these parameters based on market conditions or internal goals.