According to the put-call parity relationship, the price of a European put option with a strike price of $50 and expiration in one month should be $3, given that the corresponding call option trades for $5, the risk-free rate is 2%, and the spot price of the underlying asset (crude oil) is $52. The put-call parity relationship states that the call price minus the put price should equal the forward price minus the strike price, discounted to the present value using the risk-free rate.