Two resistors, 6 Ω and 12 Ω, are connected in parallel. What is the total equivalent resistance of the combination?

Why C is correct

Using the product-over-sum formula for two parallel resistors: Rt = (6 × 12) / (6 + 12) = 72 / 18 = 4 Ω. The result must be less than the smallest branch resistance (6 Ω), which eliminates options A and B. Option D would require a much lower individual resistance. (NEETS Mod. 1 §3-3)