Select the most suitable expression that can substitute the underlined part of the sentence without any change in meaning.
Planning to go for a movie just before the final-year examination is nothing but skating on thin ice.

The correct option is being in a risky situation.

Explanation:
The idiom "skating on thin ice" means taking a big risk or placing oneself in a precarious situation where something undesirable or dangerous could easily happen, similar to literally walking or skating over thin ice that could break.

In the given sentence, taking time off to watch a movie right before a final-year examination puts a student in a dangerous or risky position regarding their preparation and results.

Let me break down the given options:
• doing hard work: Refers to putting in effort or labor.
• being in a risky situation: Correctly captures the exact meaning of taking a major risk.
• enjoying the moment: Refers to living in the present or relaxing.
• going to hill stations: A literal and incorrect interpretation related to cold climates.

Therefore, being in a risky situation is the most appropriate substitute for the underlined idiom without altering the sentence's meaning.