In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used

ANS:B - in high range of temperature differences.

The floating tube bundle heat arrangement in a shell and tube type heat exchanger is typically used in high ranges of temperature differences. This design allows for thermal expansion and contraction of the tubes, which can occur more significantly in high temperature differentials. This flexibility helps prevent damage to the tubes and ensures efficient heat transfer. So, the correct answer would be: "in high range of temperature differences."