Neptune is one of the outer planets in our solar system. Which BEST explains why Neptune revolves in its orbit instead of moving out into space? A. Gravity pulls Neptune towards the sun.
B. Neptune's orbit is limited in its orbit becasue its so close to Jupiter.
C. Neptune's electromagnetic energy keeps it in orbit around the sun.
D. Other planets have the same mass as Neptune.

A.) Gravity pulls Neptune towards the sun.

Explanation:

Gravity is not the strongest force in nature, actually - it is quite weak in comparison to others.

But it is also the most important force in nature. Gravity is responsible for the formation of the solar system! The sun has more gravity than anything in our solar system! It keeps planets and other small bodies in a continous and elliptical orbit. The same applies to Neptune!

Also, did you know that the mass of the sun makes up 99.8% of ALL the mass in our solar system? That's pretty cool, right?

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.