Final answer:
If the transducer is above the indwelling arterial catheter, the readings will be lower than the actual pressure due to the effect of gravity on the column of blood.
Step-by-step explanation:
When using an indwelling arterial catheter to measure blood pressure, the position of the transducer relative to the catheter is critical for accurate pressure readings. If the transducer is placed above the level of the catheter, the effect of gravity on the column of blood in the tubing will result in a lower reading than the actual blood pressure within the artery. Therefore, the correct answer is b - lower than actual.