Tony is a baker who lately has had trouble getting his bread to rise sufficiently. Explain to Tony what agent he should use to ensure his bread rises and also explain how this agent works.

Tony should use yeast as an agent to ensure his bread rises sufficiently. Yeast works by consuming the sugars in the dough and producing carbon dioxide gas as a byproduct. This gas gets trapped in the dough, causing it to rise and expand. It also helps to create a moist and tender texture in the bread. Yeast is a living organism, and it thrives in warm and moist environments. To properly activate the yeast, Tony should mix it with warm water and sugar before adding it to the dough. He should also make sure the dough is kept warm and moist during the rising process.