سؤال اليوم — اختبار STEP

Read the passage and answer the question. (1) Electric vehicles, or EVs, are becoming a common sight on the world's roads. Sales have grown rapidly over the past decade, and several countries plan to stop selling new petrol and diesel cars within the next few years. Saudi Arabia has also entered the market, with plans to manufacture EVs locally and to install thousands of charging points across the country. (2) At the heart of every EV is its battery. Most use lithium-ion batteries, the same basic technology found in mobile phones, but on a much larger scale. The battery is usually the most expensive part of the car, which is why EVs have often cost more to buy than comparable petrol cars. However, battery prices have fallen dramatically, by roughly 90 percent since 2010, and the gap is closing. (3) Drivers still raise a number of concerns. The first is range, or how far a car can travel on a single charge. Early models struggled to exceed 150 kilometres, but many current models can travel more than 400. The second is charging time: while filling a tank with petrol takes a few minutes, a fast charger may need 20 to 40 minutes to reach 80 percent. The third is the effect of extreme heat, which can shorten battery life if the battery is not properly cooled. (4) Batteries also raise environmental questions. Mining lithium, cobalt and nickel uses large amounts of energy and water and can damage local landscapes. For this reason, researchers are developing batteries that need fewer rare metals, and companies are building plants to recycle old batteries and recover their materials. Consequently, the batteries of the future may be both cheaper and cleaner. Question: What is the main idea of the passage?