To much gas has build up in them? I guess
Fruits contain acids that make them sweet!
Basically, there is a presentation of types of food and the amount of those foods over 50 years in this graph. This means the graph is showing amounts of certain foods over the time period. I'm guessing that basing off of the the previous text you're just noting a change in the breaks of birds based off of the diet available to them at certain times. The adaptations and natural selection will explain the changes because due to certain limited and available foods the diet of the birds change.
It was the theory that an organism could form from something such as mud for an example.
Answer:
C. When we digest food there are tons of chemical reactions occurring in the process, they would have to break down the food which is a chemical reaction.
