Which of the following sets are subspaces of R3\mathbb{R}^3R3?
W1={(x,y,z):x+y+z=0}W_1 = \{ (x, y, z) : x + y + z = 0 \}W1={(x,y,z):x+y+z=0}
W2={(x,y,z):x+y+z=1}W_2 = \{ (x, y, z) : x + y + z = 1 \}W2={(x,y,z):x+y+z=1}
W3={(x,y,z):x2+y2=z2}W_3 = \{ (x, y, z) : x^2 + y^2 = z^2 \}W3={(x,y,z):x2+y2=z2}
W4={(0,0,0)}W_4 = \{ (0, 0, 0) \}W4={(0,0,0)}