Read the paragraph,
If you like fluffy bread, then you should be grateful for yeast. Without yeast, bread would be hard and flat. You can buy envelopes of yeast in
the grocery store. When you open the envelope, the yeast looks like a sandy substance, but you are actually looking at tiny, living, creatures, in its
dry state, the yeast is inactive, but if you add warm water to it, the yeast "wakes up," becoming active. When making bread, you add the active yeast
to a mixture that includes flour and sugar. The yeast eats the sugar and produces bubbles of gas called carbon dioxide, the same gps that people
breathe out. The bubbles make the dough rise so that your bread will be nice and fluffy after you bake it
What is the main purpose of the underlined sentence?
O 1. It provides the reader with a solution to the problem of hard and flat bread,
O2. It generalizes the role of yeast in breads and other foods made from dough,
O 3. it describes a cause and effect relationship that must occur so that bread can rise,
04. It expresses an opinion to help the reader understand why yeast is a useful ingredient,

The sentence discussing how you add water to "activate" the yeast is describing the cause and effect relationship. From the passage, we know that yeast is necessary to make fluffy, chewy bread, and for that bread to rise during baking. The cause is using the yeast in order to make bread rise, and the effect of water is the yeast activating in the dough, resulting in a rising dough during baking, and a delicious "fluffy" bread!