He's never rude. I think he's one of the most _______ boys in his class.
A:polite
B:healthy
C:beautiful
D:strong
(Ⅰ)求椭圆C的方程;
(Ⅱ)过点(0,t)作圆O的一条切线交椭圆C于M,N两点,求△OMN的面积的最大值.
请回答下列问题: