A risk analyst at a bank is teaching an intern about the use of the Arbitrage Pricing Theory (APT) to determine the expected return on a security. APT is a multifactor model that explains the returns of a financial asset. The analyst uses the following APT formula during the explanation: $R_i = E(R_i) + \beta_{i1}[I_1 - E(I_1)] + ... + \beta_{ik}[I_k - E(I_k)] + e_i$

In this context:

• $R_i$ represents the actual return on the security.
• $E(R_i)$ is the expected return on the security.
• $\beta_{ik}$ denotes the sensitivity of the security's return to the k-th factor.
• $I_k$ is the macroeconomic factor affecting the return.
• $E(I_k)$ is the expected value of the k-th macroeconomic factor.
• $e_i$ is the idiosyncratic error term, representing the security-specific risk not captured by the factors.

What is the accurate interpretation of the term $\beta_{ik}$?