Consider a force $\vec { F } = - x \hat { i } + y \hat { j }$. The work done by this force in moving a particle from point $A ( 1,0 )$ to $B ( 0,1 )$ along the line segment is : (all quantities are in SI units)\\
(1) 2\\
(2) $\frac { 1 } { 2 }$\\
(3) 1\\
(4) $\frac { 3 } { 2 }$