Currents in parallel wires ratio from resistance and area

Steps:

• Resistance R = ρL/A; same ρ, L for both, so R inversely proportional to cross-sectional area A.
• In parallel, same V across both, so I = V/R; thus I proportional to A.
• A = π(r)^2 = π(d/2)^2, so A proportional to d².
• d_S = 2 d_T, so A_S = 4 A_T; therefore I_S / I_T = 4.

Why D is correct:

• Currents ratio equals area ratio (4:1) per Ohm's law, as R_S = (1/4) R_T.

Why the others are wrong:

• A: Reverses ratio, assuming I inversely proportional to A.
• B: Assumes ratio from diameters (2:1), ignoring area dependence on d².
• C: Inverses correct ratio, confusing currents with resistances.

Final answer: D