B- yeast is used for baking things, it helps the dough rise in bread and pizzas etc
The answer is D. Supplying oxygenated blood to the arteries that travel to all major body parts.
Water and carbon dioxide are byproducts. Notice that photosynthesis and respiration are essentially the opposite of one another. Photosynthesis removes CO2 from the atmosphere and replaces it with O2. Respiration takes O2 from the atmosphere and replaces it with CO2.
Question 1: The correct answer should be the one that shows the producer first, (->) followed by the herbivore, (->) with the carnivore last.
Producers are organisms that harvest their own 'food' using things like the sunlight and water. Examples of producers are grass and other vegetation.

The herbivore, or an organism that consumes only vegetation and/or algae, consumes the producer.

⇒

The carnivore consumes meat, or other animals such as the herbivore. It's the last.

⇒

⇒

Therefore the answer is
B.
____________________________________________________________
Question 2: I'm pretty sure that succession as well as regrowth after volcanic eruption (Just look at Mount St. Helens. After 30-35 years after the eruption, nature is
still recovering) happens over time/slowly. I would say global warming [C](?) would be the answer.