Air is to be heated by condensing steam. Two heat exchangers are available $($i$)$ a shell and tube heat exchanger and $($ii$)$ a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

Finned tube heat exchanger with air inside and steam outside

Finned tube heat exchanger with air outside and steam inside

Shell and tube heat exchanger with air inside tubes and steam on shell side

Shell and tube heat exchanger with air on shell side and steam inside tubes