Correct option is (a) Foetal ECG with scalp electrode
For explanation: The following methods are commonly employed in most of the cardiotocographic monitoring during labour: I) Indirect method: Abdominal foetal electrocardiogram, foetal phonocardiogram, ultrasound techniques (narrow beam and wide-angle transducer) II) Direct method: Foetal ECG with scalp electrode (spiral, clip or suction electrode attached to the presenting part of the foetus).