There is oozing of semisolid material which forms a tough membrane over air passage. The disease is
Diphtheria is an infection caused by the bacterium Corynebacterium diphtheria. Symptoms include a sore throat, fever, barking cough, a grey or white patches develop in the throat. Diphtheria is usually spread between people by direct contact or through the air. It may also be spread by contaminated objects.
The bacterium produces a toxin called diphtheria toxin. This toxin damages tissue in the immediate area of infection usually, the nose and throat (air passage).
The semisolid material which forms a tough membrane over air passage is called the mucous membrane. The toxin damages the mucous membrane and causes the oozing of mucus.
So, the correct answer is 'Diptheria'.