Statements: 1. All satellites in geostationary orbit have an orbital period of 24 hours. 2. Satellite X has an orbital period of 12 hours. Which conclusion logically follows?

(A) Satellite X is not in geostationary orbit.

(B) Satellite X is in retrograde geostationary orbit.

(C) All satellites with 12-hour periods are lunar orbiters.

(D) Satellite X has zero orbital velocity.

Answer Key:

A

### Solution: Modus tollens: Since being in geostationary orbit requires a 24-hour period, Satellite X with a 12-hour period cannot be in geostationary orbit. Correct: A.

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