The path followed by air as it passes through the lungs in mammals is

Analyze the question: You're asked for the correct order in which air travels through the respiratory tract of a mammal after it enters the body.

Explain the concept: Air moves from larger tubes to progressively smaller ones until it reaches the tiny air sacs where gas exchange happens.

Step-by-step path of air:

1. Nostrils/mouth → pharynx → larynx (voice box)
2. Trachea (windpipe), a single large tube kept open by C-shaped cartilage rings
3. Bronchi, the trachea divides into two (left and right), one going into each lung
4. Bronchioles, each bronchus branches into many smaller tubes
5. Alveoli, tiny air sacs at the ends of the bronchioles, surrounded by blood capillaries, where oxygen enters the blood and carbon dioxide leaves

Checking the options:

• A. trachea → bronchi → bronchioles → alveoli. Correct order.
• B. Starts with the bronchi before the trachea. Wrong.
• C. Skips the bronchi. Incomplete, so wrong.
• D. This is the reverse order, the path of air leaving the lungs. Wrong.

Answer: Option A.

Exam tip: Remember the sequence "T-B-B-A": Trachea, Bronchi, Bronchioles, Alveoli. Think of it as an upside-down tree: the trunk (trachea) splits into big branches (bronchi), then twigs (bronchioles), then leaves (alveoli). Watch out for options that skip a stage, like option C.