(2022 年全国新高考 II 卷数学试题) 若 x,yx,yx,y 满足 x2+y2−xy=1{x}^{2} + {y}^{2} - {xy} = 1x2+y2−xy=1 ,则 ( )A. x+y≤1x + y \leq 1x+y≤1B. x+y≥−2x + y \geq - 2x+y≥−2C. x2+y2≤2{x}^{2} + {y}^{2} \leq 2x2+y2≤2D. x2+y2≥1{x}^{2} + {y}^{2} \geq 1x2+y2≥1