In the context of finance, the term 'beta' refers to
Explanation
Option (D) is correct because beta is a statistical measure that quantifies the volatility or systematic risk of an individual security or portfolio in relation to the movements of the overall market. Option (B) is a common distractor as it describes general portfolio management or "alpha," which focuses on active strategies to outperform the market rather than measuring relative sensitivity to it. The core concept being tested is the measurement of systematic risk within investment finance, specifically how much a stock's price is expected to fluctuate compared to a benchmark index.