The correct option is B (−^i+3^j−2^k)
Since, →r⋅→p=0
⇒ the given point lies on the equator of the dipole.
At an equatorial point, →E is antiparallel to →p
⇒ a vector parallel to →E, will be antiparallel to →p
Now, →p=(^i−3^j+2^k)×10−29
Considering all four options, the only vector that is antiparallel to →p, is (−^i+3^j−2^k)
∴→E is parallel to (−^i+3^j−2^k)
Hence, (B) is the correct answer.