Answer
The correct answer is:
(b) between $2q$ and point $P$
Work Step by Step
To the left of $q$ and to the right of $2q$, the electric field points away from both point charges, so there is no place where the electric field is zero in these two regions.
Between the two point charges, the electric fields from the point charges point in opposite directions. At point $P$, the electric field due to point charge $q$ is larger in magnitude than the electric field due to point charge $2q$. Therefore, the point where the electric field due to the two point charges is zero is between the point $P$ and $2q$.
The correct answer is:
(b) between $2q$ and point $P$
