A. Uncle Wang was bitten by a poisonous snake, so he quickly tied the upper part of the wound with a rope, cleaned the wound, and then went to a doctor for treatment. Ligation tightness is based on blocking lymphatic and venous reflux, and if it is not tightened well, A is wrong;

Xiao Yong accidentally broke his forearm while playing basketball. You should call 120 first, and seek help from teachers or hospitals as soon as possible. We can't ride home to find our parents right away. B wrong;

C, concentrated sulfuric acid has a strong corrosive, accidentally come into contact with the skin, should immediately rinse with plenty of water, and then coated with 3% ~ 5% sodium bicarbonate solution. Xiaoying and others made mistakes after class, and C made mistakes;

D. Li Yi found that her daughter who was taking a bath fainted in the closed bathroom. Dial 120, and D is correct.

So choose: D.