What is one disadvantage of using a radio ad to announce the arrival of several works by a famous painter at a local art museum? a radio ad can only play once, so it cannot reach as many people as other forms of media. b radio ad is expected to be funny, so people may think that the arrival of the painter's works is just a practical joke. c radio ad is fairly short, so it cannot give people information about when the works will be on display. d radio ad communicates ideas audibly, not visually, so it cannot let people see images of the painter's works.