Question

the substance ejected through the mouth that can be used for diagnostic purposes is known as select select mucus pleural effusion saliva sputum

Explanation:

Sputum is the substance coughed up from the respiratory tract through the mouth and can be analyzed for diagnostic purposes like detecting infections or other diseases. Mucus is a general term for a viscous secretion, pleural effusion is fluid in the pleural cavity not ejected through the mouth, and saliva is mainly a secretion for digestion and not typically used in the same diagnostic - context as sputum for respiratory conditions.

Answer:

sputum