An electric field is defined in terms of `q_(0)` a small positive charge. If the definition was in terms of a small negative charge of the same magnitude, then compared to the original field the newly defined electric field.
(a) would point in the same direction and have the same magnitude.
(b) would point in the opposite direction and have the same magnitude.
(c ) would point in the same direction and have the different magnitude.
(d) would point in the opposite direction and have the different magnitude.

Explanation

Magnitude of electric field will remain same but direction will be opposite.