The correct answer is $\boxed{\text{D}}$, 16.3 mA.
The current through a diode is given by Ohm’s law:
$$I = \frac{V}{R}$$
where $I$ is the current in amperes, $V$ is the voltage in volts, and $R$ is the resistance in ohms.
In this case, the voltage across the resistor is 4 V and the resistance is 220 Ω. Therefore, the current through
the diode is:$$I = \frac{4 V}{220 \Omega} = 0.0182 \text{ A} = 16.3 \text{ mA}$$
Option A is incorrect because it is the current through a 220 W resistor, not a diode. Option B is incorrect because it is the current through a 220 Ω resistor, not a diode. Option C is incorrect because it is the current through a 1 Ω resistor, not a diode. Option E is incorrect because it is not one of the possible answers.