Under which of the following conditions are you most likely to fall sick?
(a) When you are taking examinations.
(b) When you have travelled by bus and train for two days.
(c) When your friend is suffering from measles.
Why?

I am most likely to fall ill when the friend is suffering measles. Measles is a viral infection. It is a contagious disease. It spreads through the contact with infected mucus and saliva. The virus can even sustain on inanimate object for several hours. Even coming in contact or sharing items with an infected person results in spread of disease.