ANS:B - decreases

With an increase in temperature, the thermal conductivity of fresh lubricating oil typically decreases. Here's why:

1. Viscosity: As the temperature of the lubricating oil increases, its viscosity tends to decrease. Lower viscosity means that the oil molecules have more freedom to move around, resulting in decreased molecular interactions and reduced thermal conductivity.
2. Density Changes: In some cases, changes in temperature can also lead to changes in the density of the lubricating oil. However, the effect of density changes on thermal conductivity is generally smaller compared to the effect of viscosity changes.
3. Composition: The thermal conductivity of lubricating oil may vary depending on its composition. Different additives and base oils can affect the thermal conductivity differently. However, in most cases, the decrease in viscosity dominates the change in thermal conductivity with increasing temperature.