Ever since the 1750s, when the writer, sat

问题：

Ever since the 1750s, when the writer, satirist, statesman and inventor Benjamin Franklin put political cartooning on the map by publishing the first cartoon of the genre in America, artists have combined their talent, wit and political beliefs to create cartoons that enrage, enlighten or simply engage the viewer.

A picture may paint a thousand words, but a cartoon provokes, protests and entertains all at once. It is this that makes cartoonists so valuable and influential in times of crisis. Today, that crisis is climate change, and clever imagery can give new impetus to our struggle to combat global warming. The organizers of Earthworks 2008, a global cartoon competition, believe that art and humor are simple ways to get the environmental message across.

"We set up the competition to give cartoonists around the world a platform on which to express themselves," says John Renard, one of the Earthworks organizers. "We hoped the competition would stimulate cartoonists to use their pens and wit to help combat environmental devastation and give new impetus to our desperate fight to stop global warming," he says. "After all, humor is often a valuable key in the struggle to win hearts and minds. "

But despite the sharp wit that pervades the cartoons, climate change is no laughing matter for their creators. The 50 or so countries from which the 600 competition entries were sent are all suffering the effects of global warming, some more dramatically than others. Two cartoons were sent from Burma, where in May this year a tropical storm tore through five regions along the western coast, killing at least 100,000 people, and leaving millions more without shelter, food, or clean water.

Although governments around the world are reluctant to suggest, officially, that the disaster in Burma is a direct result of global warming, there’s little doubt that it will have added to the tropical storm’s destructive power.

Studies published in the journals Nature and Science have demonstrated a link between rising sea temperatures and increased wind-speed of tropical storms and hurricanes, and even US-government-funded organizations such as the National Oceanic and Atmospheric Administration admit that a warming of the global climate will affect the severity of storms. "Experiencing first-hand the catastrophic effects of climate change allowed these artists to give their cartoons a special sharpness," says "prevent such devastation from becoming more common. \

According to the passage, "the sharp wit" (boldfaced in Paragraph 4) that fills the competition entries refers to the cartoonists’().

A. amusing expression

B. cutting criticism

C. political keenness

D. bitter grievance