Final answer:
d) encourage the patient to pant with pursed lips
The nurse's first action should be to encourage a patient at 8 cm dilation to pant with pursed lips to control the urge to push until full dilation is reached.
Step-by-step explanation:
When a patient in labor exclaims, "I have to push!" and is found to be 8 cm dilated, the nurse's first action should be to encourage the patient to pant with pursed lips. Applying pressure to the patient's fundus or instructing to bear down is not appropriate at this stage, as complete dilation (10 cm) has not been achieved yet. Coaxing the patient in relaxation techniques could help manage their pain and anxiety but is not the most immediate need if they are feeling an urge to push. Panting helps control the urge to push prematurely and prevents potential harm to the cervix by delaying pushing until full dilation is reached.