The amount of yeast compared to the amount of the other ingredients
Yeast.
the yeast
The yeast consumes the natural sugars in the dough and causes bubbles to form. This causes the dough to rise. It's being blown up by the yeast.
Yeast.
Yeast is the ingredient used in baking that causes the dough to rise.
Pan de sal is a kind of bread, meaning that the yeast causes it to rise like it causes any bread to rise. Namely, yeast causes fermentation, and in breads, this interaction with the monosaccharides found in the dough creates carbon dioxide bubbles that cause the bread to rise.
Yeast is only used in bread products. It causes the fermentation process, which causes the breads to rise.
Carbon dioxide
It has to rise, then is worked into product (buns, loaf bread), proof (more rising), then baked.
Yeast.
The Yeast eats the sugar and realeses Carbon Dioxide which causes the bread to rise.
Without yeast, dough would not rise or bake properly.