赞题库-背景图
单项选择题

设区域D由x=0,y=0,x+y=
,x+y=1围成,若I 1 =
[ln(x+y)]dxdy,I 2 =
(x+y) 3 dxdy,I 3 =
sin 3 (x+y)dxdy,则( ).

A.I 1 >I 2 >I 3
B.I 2 >I 3 >I 1
C.I 1 <I 2 <I 3
D.I 1 <I 3 <I 1