设椭圆的参数方程为x=acosθy=bsinθ(0≤θ≤π),M(x1,y1),N(x2,y2)是椭圆上两点,M,N对应的参数为θ1,θ2且x1<x2,则( )A.θ1<θ2B.θ1>θ2C.θ1≥θ2D.θ1≤θ2