Final answer:
D. resistance decreased and pump rate decreased to maintain pressure.
When the flow tube radius increases, resistance decreases, requiring the pump rate to decrease as well to maintain constant pressure.
Step-by-step explanation:
When the flow tube radius increases, the resistance within the tube decreases. According to the principles of fluid dynamics, specifically Poiseuille's Law, for a given pressure difference, a lower resistance would allow for a higher flow rate.
However, since the aim is to maintain the same pressure within the system, the pump rate would need to be decreased to account for the decreased resistance, ensuring that the flow rate is maintained at a level that keeps the pressure constant. Therefore, the correct answer is D. resistance decreased and pump rate decreased to maintain pressure.
When the flow tube radius increased, the correct answer is D. resistance decreased and pump rate decreased to maintain pressure. This is because when the radius of the tube increases, the resistance to flow decreases. As a result, the pump rate can also decrease while still maintaining the pressure.