C

Step 1: Given that Ammeter A2 reads 4.8 A.
Step 2: Calculate the potential drop across the 10 Ω resistor using Ohm's Law:
V = I \times R
For the 10 Ω resistor:
V = 4.8 A \times 10 \Omega = 48 V.
Step 3: Determine the current through A1. Since A2 is reading 4.8 A, we know there is some distribution of current.
Assuming a parallel circuit where A1 has a different resistive path (we'll calculate later).
Step 4: Let's calculate the voltage drop across the 30 Ω resistor to find the power using the formula: P = \frac{V^2}{R} or P = I^2 \times R.
For the 30 Ω resistor, we need to calculate the total current flowing from the source.
Assuming the total current leaving the source is 4.8 A and the overall resistance in this section is 10 Ω + 30 Ω = 40 Ω.
The current can be divided based on the resistances.
Let's calculate the total current using Power: If Power is given, P = VI
where V = 48 V and R = 40 Ω, Power in the 30 Ω resistor is due to total current.
Thus the total current remains at 8.0 A through this resistor: P = 8.0 A^2 \times 30 \Omega = 640 W.
However, A3 reading 8.0 A indicates all current passes through A3.
Therefore, using the voltage drop and the numerical values given, we can confirm that A3 reads 8.0 A as an affirmative answer.
Therefore, the correct answer is option [C] 8.0.