ANS:A - give larger area per tube.

Finned tube heat exchangers do not facilitate very large temperature drops through the tube wall, nor are they typically used for smaller heat loads. Therefore, the correct option is: "Give larger area per tube." Finned tube heat exchangers are designed to increase the surface area available for heat transfer between the fluid inside the tubes and the fluid or ambient environment outside the tubes. By adding fins to the exterior surface of the tubes, the effective surface area for heat transfer is significantly increased. This allows for enhanced heat transfer rates without the need for additional tubes, making finned tube heat exchangers suitable for applications where maximizing heat transfer efficiency within a limited space is desired.