If p + q + r = a + b + c = 0, then the determinant \(\left| {\begin{array}{*{20}{c}} {{\rm{pa}}}&{{\rm{qb}}}&{{\rm{rc}}}\\ {{\rm{qc}}}&{{\rm{ra}}}&{{\rm{pb}}}\\ {{\rm{rb}}}&{{\rm{pc}}}&{{\rm{qa}}} \end{array}} \right|\) equals
1
0
2
1
3
pa + qb + rc
4
pa + qb + rc + a + b + c