Answer:
I think it's b but good luck and nice profile pic :D
The answers are;
The muscular contractions are wave-like
The muscular contractions are entirely involuntary
This action is called peristalsis.
It is powered by the expansion and contraction of the smooth muscles present in the esophagus. It is controlled by the sympathetic activity of the autonomic nervous system hence
the movements are involuntary.
The two events in earth's history with great impacts on carbon cycle is the burning of fossils fuels and the change in land use and land cover. burning of fossils fuels in homes and industries extracts the carbon from the fossil fuel and emit it as carbon dioxide in the atmosphere. change in land use such as deforestation also change the amount of carbon in circulation.
The yeast may not activate if it's way past it's expiration date. Next, add the required amount of yeast to the warm water. Feed the yeast! I like to add a little sugar or honey to the water and yeast mixture, then give it a stir.
