\({x^2} + x + {y^2} - y - 2xy\)
A.\( \left( {x - y} \right)\left( {x + y + 1} \right)\)
B.\( \left( {x + y} \right)\left( {x - y + 1} \right)\)
C.\( \left( {x - y} \right)\left( {x - y + 1} \right)\)
D.\( \left( {x + y} \right)\left( {x + y - 1} \right)\)