A、Because the dressing styles change so fast. B、Because it is hard to distinguish casual clothes from formal ones. C、Because the

Perhaps you work at an office with a stated dress code, or you’ve received an invitation to an event with the request to dress "business casual. "
    But what exactly is a business casual dress code? It turns out the answer to that question is confusing for many. Part of the problem is that there are so many trends that are so casual.
    Last June, for example, JPMorgan sent out a company-wide memo encouraging employees to dress in business casual unless they were meeting with clients. Other firms followed suit in relaxing their office dress requirements as they sought to attract millennials, many of whom like to dress in athleisure in their spare time.
    But the rise of athleisure and increasingly casual workplaces has led some people to put on leggings and other inappropriately casual clothing items for the office. Leaning into that, according to the ladies behind Of Mercer, could be a big mistake.
    You can, however, incorporate some elements of athleisure into your work wardrobe, like tailored pants that have some stretch to them—just no sweatpants, yoga pants, or tank tops.
    Our rule of thumb is to make sure you’re dressing one step above everyone around you, Emelyn Northway, Smith’s cofounder, said. "If people are wearing jeans, wear nice black pants instead. It goes a long way towards making you feel good about yourself and making other people feel like you know what you’re doing. "
    Recent studies have shown that wearing nice clothes in the office can actually be an effective strategy—dressing professionally can affect the way people perceive you, how confident you’re feeling, and even how you’re able to think abstractly.
    Questions 12 to 15 are based on the passage you have just heard.
    12.Why defining a business casual dress code so confusing?
    13.What dressing code is popular among millennials?
    14.Which of the following clothes is inappropriate at a workplace?
    15.Why is wearing nice clothes in the office is recommended?