ANS:C - > 8:1

In a moderately sized packed absorption tower, channeling occurs when the flow of the gas or liquid becomes unevenly distributed across the cross-section of the tower. This uneven distribution can lead to reduced contact between the gas and liquid phases and decreased efficiency of the absorption process. To minimize channeling, it is important to ensure uniform distribution of the gas and liquid flows across the packed bed. One way to achieve this is by maintaining an appropriate ratio of tower diameter to packing diameter. The recommended ratio of tower diameter to packing diameter to minimize channeling is typically greater than 8:1. A tower with a larger diameter relative to the size of the packing particles allows for better distribution of the gas and liquid flows, reducing the likelihood of channeling. Therefore, the correct option is > 8:1.