Select the correct text in the passage.
Which phrase in this passage is a context clue for the meaning of the word expanding?
The Sahara Desert
Deserts cover a large portion of the land on our planet. The surface land of the earth is only 29 percent. Remarkably, one-third of that land is covered by deserts. The Sahara desert in Africa is one of the largest deserts in the world. In fact, the Sahara desert makes up 8 percent of the total land area of the earth. Amazingly, the size of this desert is still expanding with every passing year. It has grown more than 250,000 square miles over the last 53 years. Antarctica is currently said to be the biggest desert on the earth. However, with the way the Sahara is growing in size, it may soon become larger than Antarctica. The Sahara may be a big piece of land, but few people live there because of the harsh weather conditions. During the day, it is extremely hot. At night, the temperatures often drop to below freezing. Yet about two million people live in this desert. When one thinks of a desert, an empty land filled with sand comes to mind. However, the Sahara desert is known to have about 1,200 different kinds of plants. This shows that certain parts of the desert are quite fertile.