In order to calculate the voltage drop in a resistor, we can use the formula below:
[tex]V=I\cdot R[/tex]If the current passing through the resistor is 3 A and its resistance is 3 ohms, so the voltage drop is:
[tex]\begin{gathered} V=3\cdot3\\ \\ V=9\text{ Volts} \end{gathered}[/tex]Therefore the correct option is b.