What is the current flowing in the circuit?

For resistors connected in series, the total resistance ($R_T$) is the sum of individual resistances.

$$R_T = R_1 + R_2$$ $$R_T = 8 \, \Omega + 4 \, \Omega$$ $$R_T = 12 \, \Omega$$

Ohm's Law states that current ($I$) is equal to voltage ($V$) divided by resistance ($R$).

$$I = \frac{V}{R_T}$$

Given $V = 48 \, V$ and $R_T = 12 \, \Omega$:

$$I = \frac{48 \, V}{12 \, \Omega}$$ $$I = 4 \, A$$

The current flowing in the circuit is $4.00 \, A$. This corresponds to option B.