Which of the following concepts relates to the risk associated with the size of the company?

The concept that relates to the risk associated with the size of the company is the company size premium. This refers to the phenomenon in which smaller companies tend to have higher risk-and-return profiles compared to larger, more established firms.

Investors usually demand a higher return for investing in smaller companies because these firms may face greater operational risks, less access to capital, and higher volatility in earnings. Consequently, this increased risk expectation translates into a company size premium, which compensates investors for the additional risks related to investing in smaller firms.

The company size premium is often used in capital asset pricing models and other financial analyses to adjust expected returns based on the size of the investment. In contrast, the other options do not specifically address the relationship between risk and company size. The equity risk premium relates to the additional return expected from investing in stocks over risk-free assets. Comparative industry risk assesses the risk of a company relative to others in the same industry, and interest income pertains to the earnings from investments in bonds or similar securities, not to the company's size.