Which of the following words is closest in meaning to “Yeast”?

Yeast means a fungus used in brewing and baking.

• Correct answer - a substance used in brewing and baking: it has the same meaning as Yeast.
• food for the insects: food eaten by bugs - wrong, it does not mean the same as Yeast.
• food for the animals: fodder - wrong, it does not mean the same as Yeast.
• food for human beings: nourishment for people - wrong, it does not mean the same as Yeast.