Final answer:
To solve the given problem of branches breaking and meeting up at certain points, we need to analyze the circuit using the loop rule and the junction rule. Based on the equations provided, the correct answer is option A: ST12 & ST30.
Step-by-step explanation:
The question is asking about the branches breaking and meeting up at certain points, labeled ST. To solve this problem, we need to use the loop rule and the junction rule to analyze the circuit.
Based on the given equations, the loop rule equation for the loop abe fa is I₁ R₁ + I₂ R₂ = V₁, and the loop rule equation for the loop ebcde is I₂ R₂ − I₃ (R₃ + R₄) = V₂.
By applying the junction rule at point e, we can see that I₁ flows into the junction, while I₂ and I₃ flow out. Since applying the junction rule at e produces the same equation as before, we need three independent equations to solve the problem, so the loop rule must be applied. Therefore, the correct answer is option A: ST12 & ST30.