⑴I'm hungry.____                       A. She's running.

⑵What are you doing?____       B. He's making noodles.

⑶What are they doing?____      C. I'm hungry, too.

⑷What is she doing?____          D. They are rowing a boat.

⑸What is Sam doing?____         E. I'm reading a book.

自然界中氧气的产生与消耗，构成了自然界中的氧循环，下列选项不属于氧气在大自然中消耗的途径的是（　　）