Common cold is caused by:

The correct answer is Option (2) → Rhino virus

The common cold is one of the most infectious human diseases. It stays in the upper air passages and does not reach the lungs. It spreads through droplets from the cough or sneeze of an infected person.

Option (1) Streptococcus pneumoniae — Incorrect. This bacterium causes pneumonia, an infection of the alveoli of the lungs.

Option (2) Rhino virus — Correct. Of the four, only the rhino viruses cause the common cold; the other three cause pneumonia or ringworm.

Option (3) Haemophilus influenzae — Incorrect. It is the other bacterium the book names as a cause of pneumonia.

Option (4) Microsporum — Incorrect. It is a fungus that causes ringworm.

NCERT Extract:
Common Diseases in Humans – “… Many viruses also cause diseases in human beings. Rhino viruses represent one such group of viruses which cause one of the most infectious human ailments – the common cold. They infect the nose and respiratory passage but not the lungs. The common cold is characterised by nasal congestion and discharge, sore throat, hoarseness, cough, headache, tiredness, etc., which usually last for 3-7 days.”