Which of the following popular sayings is an example of a true scientific theory?

Eating lots of carrots will improve your eyesight. It is safe to eat dropped food if you adhere to the 5-second rule. Drinking warm milk makes you sleepy. Touching toads gives you warts.

The carrot myth was invented by the English Airforce to hide their radar system during WW (1 or 2, I'm not sure). Dropped food doesn't matter because dust and bacteria the food touches are on it the moment it hits the ground. Touching toads doesn't give warts, however the poison he secretes from its skin (a toad is poisonous, not venomous) can irritate. So it must the warm milk.