If the current flowing through 3 ohm resistor is 0.8 ampere in the given circuit, then what is the potential drop across the 4 ohm resistor?

Answer & explanation
Correct answer: option 2
$\text{If Current through 3}\Omega \text{ is } I_1 \text{and Current through 6}\Omega \text{ is } I_2$
$\text{then } I_2 = \frac{R_1}{R_2} I_1 = 0.4 A$
$\Rightarrow \text{Current through 4}\Omega = I_1 +I_2 = 1.2A$
$\Rightarrow V = IR = 4.8V$