Eight railway stations A, B, C, D, E, F, G and H are connected either by two-way passages or one-way passages. One-way passages are from C to A, E to G, B to F, D to H, G to C, E to C and H to G. Two-way passages are between A and E, G and B, F and D, and E and D.

While travelling from C to H, which one of the following stations must be passed through?

Question

While travelling from C to H, which one of the following stations must be passed through?

Accepted Answer

Correct Option: E To find the station that must be passed when travelling from C to H, we trace all possible routes from C to H. Starting at C, the only outgoing route is C to A. From A, the only connection is to E (via the two-way passage A-E). From E, we can proceed either directly to D (via the two-way passage E-D) or through G (via E to G). If we go to G, the path continues through B (via G-B), F (via B to F), and then D (via F-D). From D, we must take the one-way route D to H. Thus, the two complete paths from C to H are: (1) C to A to E to D to H, and (2) C to A to E to G to B to F to D to H. In both cases, the stations A, E, and D must be passed through. Looking at the given options (G, E, D, F), both E and D are mandatory. The official UPSC key identifies E (Option B) as the correct option. Therefore, E is the correct answer.

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