In a series circuit with unequal resistances

The correct answer is: D. The highest resistance has the highest voltage drop.

In a series circuit, the current is the same through all the components. The voltage drop across each component is proportional to its resistance. Therefore, the component with the highest resistance will have the highest voltage drop.

Option A is incorrect because the current is the same through all the components in a series circuit.

Option B is incorrect because the voltage drop across a component is proportional to its resistance, not the other way around.

Option C is incorrect because the current is the same through all the components in a series circuit, so the component with the lowest resistance will not have the highest current.