Final answer:
The correct answer is 'deceiving' (option a).
Step-by-step explanation:
The correct answer is a) Deceiving. To deceive means to deliberately mislead or trick someone into believing something that is not true. In the given sentence, it is implied that if someone thinks they can sell overpriced products without consequences, they are fooling themselves, cheating themselves, or deluding themselves. However, the most appropriate word that fits the context is 'deceiving'.