The wavelength (\(\lambda\)) of a wave can be calculated using the formula:
\[ \lambda = \frac{v}{f} \]
where:
- \(v\) is the speed of the wave,
- \(f\) is the frequency.
Given:
- Speed (\(v\)) = 9000 m/s
- Frequency (\(f\)) = 12 Hz
Substituting the values into the formula:
\[ \lambda = \frac{9000 \text{ m/s}}{12 \text{ Hz}} = 750 \text{ m} \]
So, the wavelength of the earthquake wave is 750 m.
The correct answer is A) 750 m.