题目1单选题
函数<img src="http://p.ananas.chaoxing.com/star3/origin/7c6dc1f4ed5d27c34d37277e121c9196.png">的定义域是()A. <img src="http://p.ananas.chaoxing.com/star3/origin/f6036205a353fff439f7385702cc0646.png">B. <img src="http://p.ananas.chaoxing.com/star3/origin/d87500400903981ce17a5c932a35ae09.png">C. <img src="http://p.ananas.chaoxing.com/star3/origin/6eb944399d2b70eac08c53ef6970c352.png">D. <img src="http://p.ananas.chaoxing.com/star3/origin/c5631fa6a290ad7321c93b8c44a02a14.png">