All the following in the Light's criteria are suggestive of exudative pleural effusion except -

• A. Pleural fluid protein : serum protein ratio > 0.5
• B. Pleural fluid ADA < 16
• C. Pleural fluid LDH : serum LDH ratio > 0.6
• D. Pleural fluid LDH > two thirds of the upper limit of serum LDH