Choose the correct sentence (advanced grammar):

Choose the correct sentence (advanced grammar):

Choose the correct sentence (advanced grammar):

Read the passage: \'Renewable energy sources like solar and wind now account for 30% of global electricity. However, their intermittency requires advanced battery storage systems to ensure consistent supply.\' What is the main challenge mentioned?

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Read the passage: \'The Amazon rainforest produces 20% of the world\'s oxygen. Despite its importance, deforestation continues at an alarming rate, destroying approximately 10,000 square kilometers annually.\' What is the main idea?