What best defines the concept of 'sensitivity' in investments?

The concept of 'sensitivity' in investments primarily relates to how much the price or value of an investment responds to changes in market conditions, particularly changes in interest rates or market trends. This sensitivity is often measured through the use of various metrics such as duration for bonds or beta for stocks—both of which quantify the level of risk exposure to market fluctuations.

An investment that is highly sensitive will experience larger price movements in response to changes in the market, indicating a greater risk exposure. This relationship is crucial for investors as they aim to gauge how external factors could potentially impact their portfolio's performance. Understanding sensitivity allows investors to make informed decisions about asset allocation and risk management.

The other options, while relevant factors in the context of investments, do not specifically capture the essence of 'sensitivity' as it pertains to the response of investment valuations to market changes.