A low pass filter is designed to allow signals with frequencies below the cutoff frequency (250 Hz in this case) to pass through while attenuating higher-frequency signals.
ECG (Electrocardiogram) and EEG (Electroencephalogram) typically contain low-frequency signals, so a low pass filter with a 250 Hz cutoff is suitable for these.
EOG (Electrooculogram) signals also generally have lower frequencies and would be captured appropriately by the filter.
However, the EMG (Electromyogram) records muscle activity, which contains high-frequency components (usually 20 Hz to 500 Hz), and thus, the low pass filter with a cutoff of 250 Hz would not be suitable for EMG recordings, as it would attenuate important signal components.