Given:
A figure of the electric field lines.
To find:
The nature of the charges.
Explanation;
The electric field lines always start at a positive charge. And the electric field lines always end at a negative charge. If there is a single charge, the field lines may start at infinity or end at infinity.
Electric field lines also do not form closed loops. They do not cross each other.
In the figure, the field lines start at the blue charge and end at the charge represented by the color yellow.
Therefore the blue charge is positive and the yellow charge is negative.
Final answer:
Therefore the correct answer is option B.