Which factor plays a key role in determining the premiums in the insurance industry?

The factor that plays a key role in determining premiums in the insurance industry is the insurer's investment returns. Insurance companies collect premiums from policyholders and invest those funds to generate returns. The profitability of these investments can influence how much premium the insurer needs to charge to cover not only the anticipated claims but also to maintain solvency and profitability.

When an insurer achieves strong investment returns, it may have the flexibility to lower premiums or provide better benefits to policyholders, as the returns can offset some of the costs associated with claims. Conversely, if investment returns are lower than expected, the insurer may need to increase premiums to ensure that sufficient funds are available to meet their obligations.

The other factors mentioned also play a role but are not as central to the determination of premiums. For example, while a policyholder's gender can be relevant to underwriting practices and risk assessment in certain types of insurance, it does not broadly determine premium levels across the entire industry. Similarly, the number of claims filed by competitors does not directly affect an individual insurer's pricing strategy; each insurer bases its premiums on its own loss experience and overall financial strategy. The marketing strategy can influence how a product is presented to consumers, but it does not fundamentally determine the underlying pricing mechanics of the insurance premiums