An investor who owns stock and buys a put option on that stock is using a strategy called a:

Why A — Protective put (married put)

A protective put (also called a married put) involves owning the underlying stock and buying a put option as insurance. The put sets a floor on the maximum loss — the investor can always sell at the strike price regardless of how far the stock falls. The cost is the put premium. This is like buying insurance on a stock position. A covered call (B) involves selling a call while owning stock.