The Pilatus PC-7 is a turboprop trainer aircraft designed and manufactured by Pilatus Aircraft of Switzerland.
It is widely used by air forces across the world for pilot training.
The aircraft features a single engine, tandem seating for instructor and trainee, and is recognized for its reliability and cost-effectiveness.
India also inducted the Pilatus PC-7 Mk II into the Indian Air Force as a basic trainer aircraft.
The other options are incorrect because:
- (A) Frigate: A warship, not relevant here.
- (B) Aircraft carrier: A large naval ship carrying fighter planes.
- (C) Ship: General water vessel, not applicable.
- (D) Submarine: An underwater vessel.
Thus, the correct choice is:
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\boxed{\text{Aircraft}}
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