Which of the following sets is a subspace of R2\mathbb{R}^2R2?
W={(x,y):x+y=1}W = \{(x, y) : x + y = 1\}W={(x,y):x+y=1}
W={(x,y):x2+y2=0}W = \{(x, y) : x^2 + y^2 = 0\}W={(x,y):x2+y2=0}
W={(x,y):x≥0,y≥0}W = \{(x, y) : x \ge 0, y \ge 0\}W={(x,y):x≥0,y≥0}
W={(x,y):y=2x}W = \{(x, y) : y = 2x\}W={(x,y):y=2x}