A recent article in The New York Times noted that Hollywood types now are wearing flip-flops(拖鞋)-- shoes appropriate for beachcombers--to business meetings. Decades ago, Californians were forgiven their sloppy attire as unique to their somewhat frivolous culture. Elsewhere during that bygone era, people were careful how they dressed when seen in public and certainly when going to the office. No one would think of traveling by plane in shorts or wearing anything but their best clothes for attending a church service, concert, wedding, or funeral. Look at old newsreels of baseball games and you will see most of the men in a shirt and tie. Walk through an airport today and you have to strain to find a man wearing a jacket (forget the shirt and tie) or a woman in a nice shirt. If so, they clearly are over 60. The standard for dressing down continues to decline. Neckties and suits no longer are fashionable; male models think it cool to have a face full of stubble(胡子茬). A rock star slouches onto the stage in his undershirt. Think about it: Dean Martin never failed to appear in Las Vegas in anything but his tux, and Frank Sinatra always was dressed to the nines when seen in public. That was the standard. Dress reflects many things about us and our culture. It tells us about standards, deportment, pride, and character. Somewhere along the way, our elites lost their self-confidence. Codes of dress fell by the wayside and, with them, standards of language and behavior. In a world stable and peaceful with no enemies lurking in the shadows to do us unspeakable harm, why would it matter what standards of courtesy we follow Life would go on as it is. Sadly, this is not a relaxed era such as the 1990s. It matters now what kind of the society we are. We must recapture the seriousness of a generation that won World War II and persevered through the Cold War. We may be involved in a struggle even more lengthy, deadly, and demanding than the Cold War. The watchwords must be sacrifice, vigilance, and determination. A sloppy, self-indulgent culture will not produce an effective effort against an enemy as fanatical as the Japanese Kamikaze(日本神风敢死队) pilots. Our seriousness in World War II and the early Cold War reflected the qualities of a generation of American leaders, embodying the virtues of public spiritedness, selflessness, courage, and integrity. These leaders were human and made mistakes, but they set the tone for an entire era. Their tough-minded policies and dignified appearance reflected their character. That is why it matters how we present ourselves in public. For in a time as serious as theirs-- and ours-- it is character that eventually will triumph. The underlined word "frivolous" (Line 3, Paragraph 1) most probably means ______.

A. colorful and variable.
B. playful and not sensible.
C. mysterious and attractive.
D. artistic and romantic.