A、Money. B、Message. C、Media. D、Market. C录音提到系统的广告计划应该包含四个“M”，分别是市场(Market)、媒体(Media)、花费(Money)和信息(Message)。因此选C项。

Last time we were talking about the need for advertising. Now, let’s look at how you can successfully call attention to the service or product you want to sell. To succeed, you’ve got to develop a systematic approach. But what does a systematic advertising plan look like? Well, it covers what we call—the "Four Ms": Market, Media, Money, Message. All are important areas to focus on when creating your advertising plan.
    The First step is to look at your Market, that’s the people who might become customers, buyers of your service or product. You need to know all about your possible customers: Who are they? What age group are they? What do they like, or dislike? How do they shop?
    Next, Media. You need to figure out: Which media you should advertise through? Which media will reach your intended audience? So, you do research, trying to determine which media will reach the most potential customers for the lowest cost. For instance, if you have a product, that teachers would like, then teachers are your market. So you ask yourself: What magazines do the majority of teachers read? What TV programs do teachers watch? Do teachers listen to much radio? At what times of the day?
    The third M—Money. You have an advertising budget to spend, but how do you spend it wisely. Again, research is the key: When to advertise? Or how to get the best rates? Like, maybe you’re advertising sports equipment, and you have been spending most of your budget during the holiday season when people buy gifts for each other. Now, in theory, that would seem a great time to advertise, but a research may show you’re wrong, that the customers who buy sports equipment tend not to give it as a holiday gift, but want to use it themselves. In that case, advertising during a different season of the year might give you better results.
    OK, finally, there is your Message: What do you want to say about your product? Why will buying it make the customer’s life easier, or safer or better somehow. Whatever the message is, make sure you get it right. For example, there was this Soup Shop, the soup was really tasty, but there weren’t a lot of customers. The owner thought that may be if they give something away for free with each purchase, then more people would come buy soup. So they got some cheap socks, and they advertise to give a pair away with each bowl of soup. But, then even fewer people came to the restaurant. Well, you can imagine why. People started to associate the soup with feet: they began to imagine the soup smelled like feet. The advertising massage, soup means free socks, was a bad choice.
16 What is the second "M"?
17 Why shouldn ’t we advertise sports equipment during holiday season?
18 Why does the soup shop lose its customers?