ANS:D - first decreases, and then increases

For water, when the pressure increases, the viscosity typically decreases. Here's an explanation:

• Viscosity: Viscosity is a measure of a fluid's resistance to flow. For water, viscosity decreases with increasing temperature and generally increases with increasing pressure.
• Effect of Pressure: Increasing pressure on water typically compresses its molecular structure slightly, reducing the space between molecules. This compression leads to a decrease in viscosity because the molecules can move more freely past each other under higher pressure, resulting in lower resistance to flow.
• Temperature and Pressure: While temperature primarily affects water viscosity more prominently, pressure also plays a role. At normal pressures and temperatures, the effect of pressure on water viscosity is relatively small compared to temperature changes. However, in general, increasing pressure tends to decrease water viscosity.