A WWF report shows that biological species are dying faster than ever before. There are currently 13,000 rhinos in Africa, and the number of such behemoths once reached 1 million on this continent. In Africa, The number of hippos has fallen by 95%, and there are now only 1,300 hippos, and 30 years ago, the number of this thick-skinned animal reached 29,000. At least 800 hippos' teeth and meat are traded each year in Africa. What is the correct understanding of this paragraph? ['The main function of WWF is to focus on and protect the biological species of the earth.', 'The number of hippos worldwide has fallen by 95% in the past 30 years.', 'Now things die much faster than other kinds of animals.', 'Human activity is the main reason for the sharp decline in the number of horses.']