请阅读下面的文章，并据此回答问题：
科学家在研究大气中CO2的浓度变化会对地球的平均气温造成什么影响的问题时，采用的研究途径之一是：研究古气候大气中CO2的浓度变化和当时大气平均温度的变化关系．
Hello! Welcome to my show(欢迎参观我的展览). They're my animals. Look! The lion has got a blue shirt. The tiger has got a red hat. The monkey has got a yellow skirt. The panda has got a green T-shirt. Has the elephant got a brown sweater? No, he hasn't. He has got an orange sweater. That's very funny.
A. B. C. D. E.
如果a>0，那么a+1a+1的最小值是（ ）
B. 
C. 
D. 
E. 
