The common cold is an infection of the upper respiratory tract caused by different virus. It is called "common cold" because it is one of the most common infectious diseases in humans. The infection is usually mild and improves without treatment
o a. Difficulty in breathing
O b. More than 100 viruses
O c. The common cold
O d. Upper respiratory tract pls need ko na po yung answer
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Answer:
d. Upper respiratory tract
Explanation:
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