The figure shows the electric field lines around a conductor.
(a) At which of the four points is the field strongest?
(b) At which point is there a negative charge?

a) At the sharp turning, field strength will be high. At point D sharpness of curve is more in comparison with another point , So Point D will be the answer.

b) field lines converge to a negative charge and diverges to a positive charge.

Hence $D$ has (-)ve charge