Combination of Resistors question from NEET 2020 (Phase 2)

Answer: (c)

1. The upper $4\ \Omega$ and $8\ \Omega$ meet at the apex, so they are in series: $12\ \Omega$.
2. This $12\ \Omega$ is in parallel with the $6\ \Omega$: $\dfrac{12 \times 6}{18} = 4\ \Omega$.
3. In series with the lower $4\ \Omega$ and $8\ \Omega$: $R_{AB} = 4 + 4 + 8 = 16\ \Omega$.
4. So the answer is (c) $16\ \Omega$.