A perforated plate has holes of diameter d n arranged in a pitch p h . Each hole has a tube of I.D. d t passing through it. The ligament efficiency is given by

• A. ( p h - d h )/ p h
• B. ( p h - d h . d t /2)/ p h
• C. ( p h - d t )/ p h
• D. ( p h - d h )/ d h