Correct option is (c) 1-2 cm / min
Explanation: Normally, accuracy of measurement of foetal heart rate may be 2-3% for classification for responses. Sensitivity of 20 bpm /cm of the recording chart allows adequate reading of the recorder FHR. Labour activity and FHR traces are usually recorded simultaneously on the same time scale. Chart speed of 1-2 cm/min is adequate to provide sufficient resolution of the stimulus-response relationship.
