Which of the following elements is released into the atmosphere by all of these processes: volcanic outgassing, animal respiration and flatulence, burning of fossil fuels, and metamorphism of limestone?
a. carbon.
b. nitrogen.
c. oxygen.
d. sulfur

a. Carbon

Explanation:

During volcanic outgassing is a process whereby volcanic eruptions emits gases to the atmosphere. Examples of gases released are carbon dioxide and water vapor. The respiration of animal takes in oxygen and gives out carbon dioxide. Flatulence is the release of gas (i.e. carbon dioxide) from the digestive system out of the back passage. The burning of fossil fuel also releases carbon dioxide. Metamorphism of limestone is when limestone is subjected to pressure and heat. Carbon is the element that is present in all these processes.

samuel de champlain. in 1608, king henry iv sponsored pierre dugua, sieur de mons and samuel de champlain as founders of the city of quebec with 28 men. this was the second permanent french settlement in the colony of canada.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.