【正确答案】 B

【答案解析】[解析]
Tyler was born infected with HIV; his mother was also infected. From the very beginning of his life, he was dependent on medications to enable him to survive. When he was five, he had a tube surgically inserted in a vein in his chest. This tube was connected to a pump, which he carried in a small backpack on his back. Medications were hooked up to this pump and were continuously supplied through this tube to his bloodstream. At times, he also needed supplemented oxygen to support his breathing.
Tyler wasn"t willing to give up one single moment of his childhood to this deadly disease. It was not unusual to find him playing and racing around his backyard, wearing his medicine—laden backpack and dragging his tank of oxygen behind him in his little wagon. All of us who knew Tyler marveled at his pure joy in being alive and the energy it gave him. Tyler"s morn often teased him by telling him that he moved so fast she needed to dress him in red. That way, when she peered through the window to check on him playing in the yard, she could quickly spot him.