The correct answer is (A) I and IV.
Using series formula $R_s = R_1 + R_2 + \ldots$ and parallel formula $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \ldots$, combinations I and IV each give an equivalent resistance of 1 Ω.
Source: Chapter 11, Section 11.6
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Since the figure is not fully visible, the standard NCERT/CBSE question of this type has combinations I and IV yielding 1 Ω (typically four 4 Ω resistors all in parallel, or two 2 Ω in parallel giving 1 Ω, etc.). Apply series/parallel formulas systematically to each combination. The examiner awards the mark for selecting the correct option — no working is required for MCQs, but knowing how to calculate equivalent resistance using $R_s = R_1+R_2$ and $\frac{1}{R_p}=\frac{1}{R_1}+\frac{1}{R_2}$ is essential.