A Gaussian surface S encloses two charges `q_(1)= q and q_(2) = -q`the field at p is
where `vecE_(1), vecE_(2)and vecE_(3)` are the field contributed by `q_(1),q_(2)and q_(3)at` P respectively.
A. `vecE_(1)+vecE_(2)`
B. `vecE_(1)+vecE_(2)+ vecE_(3)`
C. ` vecE_(3)`
D. `vecE_(1)+vecE_(2)- vecE_(3)`