Step 1: Analyzing Option Payoff Profiles:
Let us examine the payoff of a long option position at expiration. For a call option, the payoff is $\max(0, S_T - K)$ minus the premium paid ($P$).
Step 2: Evaluating Downside Risk:
If the market moves unfavorably, the option buyer will simply let the option expire unexercised. The value of the option contract drops to zero.
Step 3: Quantifying the Absolute Downside:
Since the option buyer cannot lose more than the upfront cost of the contract, their maximum loss is strictly limited to the option premium paid (C).