Answer the following question given this paragraph: Bronchitis is an inflammation of the bronchi, the air passages that conduct air into the lungs. The bronchi become red and swollen with infection. Acute bronchitis is usually caused by viruses or bacteria, and may last several days or weeks. It is characterized by a cough that produces phlegm, or mucus. Symptoms include shortness of breath and wheezing. Acute bronchitis is usually treated with antibiotics. Q: What is the usual treatment for acute bronchitis? A:

Options: 1). surgery 2). physical therapy 3). pesticides 4). antibiotics
The answer is:
4).