ANS:D - All (a) (b) and (c).

The use of finned tubes in a multipass shell and tube heat exchanger increases all of the following parameters:

1. Tube side pressure drop and the heat transfer rate: The addition of fins to the tube surface increases the surface area available for heat transfer. This increased surface area enhances heat transfer between the tube side fluid and the surrounding environment. However, the presence of fins also increases the pressure drop on the tube side due to increased frictional resistance.
2. Convective heat transfer coefficient: Fins on the tube surface disrupt the flow of fluid, promoting turbulence and enhancing convective heat transfer. This results in an increase in the convective heat transfer coefficient, which represents the efficiency of heat transfer between the fluid and the tube surface.
3. Effective tube surface area for convective heat transfer: The addition of fins significantly increases the effective surface area available for convective heat transfer. Fins extend the surface area of the tube, allowing for greater contact between the fluid and the tube surface. This increased surface area enhances heat transfer efficiency.

Therefore, the correct answer is All (a) (b) and (c). The use of finned tubes in a multipass shell and tube heat exchanger leads to improvements in tube side pressure drop, heat transfer rate, convective heat transfer coefficient, and effective tube surface area for convective heat transfer.