The subject matter of an option refers to the assets you choose to buy or sell. Including stocks, national debt, currency, stock index, commodity futures and so on. Options are derived from these subject matter, so they are called derivative financial instruments.
It is worth noting that the option seller does not necessarily own the underlying assets. Options can be "short". Option buyers may not really want to buy the underlying asset. Therefore, when the option expires, both parties do not have to make physical delivery of the subject matter, but only need to make up the price according to the price difference.
Extended data:
The price used to buy and sell the underlying assets when exercising options. In most options traded, the underlying asset price is close to the exercise price of the option. The exercise price is clearly stipulated in the option contract, which is usually given by the exchange in the form of decreasing or increasing according to certain standards, so there are several different prices for options with the same target.
Generally speaking, when an option is just traded, each option contract will give several different exercise prices at certain intervals, and then increase according to the changes of the underlying assets.
As for how many exercise prices each option has, it depends on the price fluctuation of the underlying assets. When investors buy and sell options, the general principle of choosing the exercise price is: choose the exercise price with active trading near the underlying asset price.