✔ 最佳答案
It is talking about underlying asset or instrument of derivatives. Derivatives means financial products that are developed and related with the underlying asset or instrument. For example, a stock call option has strike price of HKD 130, time to maturity of 3 months and underlying asset: stock such as Hong Kong bank. The price of the call option will depend on the current Hong Kong bank stock price, time to maturity and volatility of the underlying stock.