The equation of the line joining the origin to the point of intersection of the lines \(\frac{{\rm{x}}}{{\rm{a}}} + \frac{{\rm{y}}}{{\rm{b}}} = 1\) and \(\frac{{\rm{x}}}{{\rm{b}}} + \frac{{\rm{y}}}{{\rm{a}}} = 1\) is
1
x - y = 0
2
x + y = 0
3
x = 0
4
y = 0