Final answer:
The maximum frequency that can be present in the analog signal without causing aliasing is 1.25kHz, as determined by the Nyquist Theorem, which is half of the sampling frequency of 2.5kHz.
Step-by-step explanation:
The question relates to determining the maximum frequency that can be present in an analog signal to avoid aliasing, given a sampling frequency. According to the Nyquist Theorem, the sampling frequency must be at least twice the maximum signal frequency. Thus, the maximum frequency that can be present without causing aliasing is half the sampling frequency.
In this case, the sampling frequency is 2.5kHz. Therefore, the maximum frequency without aliasing is 2.5kHz / 2 = 1.25kHz.