Pick out the wrong statement pertaining to the design of the bubble cap tray of a distillation column to give stable operation and even vapour distribution.

• The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation.
• Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps.
• The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4.
• none of these.