Read the following article and answer the question. Article: What would you think if someone suggested knocking down St Paul's Cathedral to widen the road? Or pulling down Big Ben to make way for a car park? It would be ridiculous, right? But when it comes to devastation of the natural world, we aren't so easily shocked. But we should be...or we'll be in a lot of trouble. _ . Ancient forests are destroyed. Wetlands are becoming dry. Woodland is disappearing, and all in the name of progress. This is bad in itself, but it's devastating for biodiversity. Biodiversity refers to the variety of plants, animals and other living things that are all interconnected. The ecological services provided by biodiversity are vital to everyday life. The air we breathe is a product of photosynthesis by green plants. Insects, worms and bacteria break down waste and make soils rich. And tiny organisms clean the water in rivers and sea. In fact, all life on the earth exists thanks to the benefits of biodiversity. More than 90 percent of the calories consumed by people worldwide are produced from 80 plant species. And 30 percent of medicines are developed from plants and animals. Maintaining a wide diversity of species in each ecosystem is necessary to preserve all living things. The loss of biodiversity could be devastating. "It is wrong to think that biodiversity can be reduced indefinitely without threatening humans," said Harvard University biologist Edward O. Wilson, known as the "father of biodiversity". He warned, "We are about to reach a critical point beyond which biodiversity loss will become irreversible ." But what can we do? The present problem is that the concept of biodiversity is so vague . People might care about giant pandas, but it is much harder to excite them about the fate of tiny sea creatures which are being boiled to death in the cooling systems of power stations along coastlines. TheGuardiannewspaper is trying to help. _ has launched the Biodiversity 100 campaign to try to convince governments around the world to take action to deal with the widespread... Question: When it comes to biodiversity, the present problem is that _ . Answer:

Available options:
a). people might not clearly know what is biodiversity and what should be protected;
b). people are not aware that giant pandas are endangered;
c). people don't realize that biodiversity is vital to everyday life;
d). people hunt sea creatures for food;
The answer is:
a).