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The heading rose of an HSI is frozen on 200°. When the aircraft is lined up on the centerline of the ILS localiser for runway 25, the localiser needle will be:
  • A
    centered.
  • B
    left of the center.
  • C
    centered with the fail flag showing.
  • D
    right of the center.

HSIs (Horizontal Situation Indicators) consist of a slaved gyrocompass, with a CDI (course deviation indicator) in the middle. This CDI can be twisted to face in any direction on the HSI, and the direction it is facing is its chosen course, similar to moving the OBS knob on a standard CDI.

This question mentions that HSI becomes fixed, with its heading staying in one direction. It did not say if we would still be able to swivel the CDI around inside the HSI, but it does not matter anyway.

A CDI does not need a selected course to be able to to show the indications from an ILS. An ILS receiver simply works by measuring the difference in depth of modulation between a two signals (that is for the localiser, the same thing happens again at a different frequency for the glide path), and does not require any input from the OBS. Therefore, the CDI in the middle of the HSI will continue to do its job on the approach, no matter what the heading is showing and which direction it is facing.

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