D

The unit of electric field ( ext{E}) is defined as force per unit charge, which can be expressed in SI units as:
$$ ext{[E]} = \frac{[F]}{[q]} = \frac{[N]}{[C]} = \frac{[kg \cdot m/s^2]}{[C]} = \frac{kg \cdot m}{C \cdot s^2} $$
Given Options Analysis:
The unit Volt per meter (V/m) is indeed equivalent to electric field.
Option A with the unit \( N/C \) is also equivalent to electric field.
Option B representing \( J/(C \cdot m) \) is not a standard equivalent for electric field.
Option C, which is \( V/m \), is also an equivalent for electric field.
Therefore, the answer that is not equivalent to the unit of electric field is option D (the unit provided does not correspond to electric field).