Choose the correct answer. I've just heard that Nick ... his car, did you know?

The sentence is in the present perfect passive voice, indicating an action completed in the past with a present result. The correct form is 'has sold' or 'was sold'. Since 'has sold' is not an option and the context implies the car was sold by Nick, 'was sold' is the most appropriate choice among the given options. The word 'selled' is not a correct English word; the past participle of 'sell' is 'sold'. 'Sells' is present simple active, which doesn't fit the context. Therefore, 'was sold' correctly completes the sentence to convey that Nick's car has been sold.

The correct answer is: was sold