"Varying Doppler shifts of the stars" is no longer the correct answer.
Since the big chunk of data was published in 2012 from the Keppler mission, transit photometry has far supersceded the radial velocity method (which uses Doppler spectroscopy) in the number of exoplanets discovered. (See 3rd paragraph in https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanetsRadial_velocity)
Therefore, the correct answer now is most definitely "The planet blotting out the light of the star".
Nuclear fusion is a process in which the atomic nuclei that has a low atomic number fuses to form a much heavier nucleus through the release of energy. Basically this is the process of combining two or more lightweight nuclei in order to form one heavier nucleus.
Lighter elements like hydrogen and helium are generally more fusible. Heavier elements are subject to a different process call nuclear fission. During this process a heavier nucleus splits either spontaneously or on impact with another particle and releases energy this way.
Correct answer option B and E
Kepler’s laws of planetary motion are 3 laws stating the motion of planets around the Sun. They include:
All planets move about the Sun in elliptical orbits, having the sun as one of the foci.
A line that connects a planet to the Sun sweeps out equal areas in equal lengths of time.
The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit.
Option B, which states that the force of attraction between two objects decreases as the distance between them increases is Newton’s Law of Universal Gravitational.
Option E is part of the answer because not all are part of Kepler’s Laws.
Greenwich is a section of London, England that is well-known for being the Prime Meridian line. This line is located at zero degrees longitude. The significance of this line is that it separates the eastern and western hemispheres. Specifically, the exact meridian place is at the Royal Observatory. This line passes from pole to pole. The line was established in the early 1700s.
At first, England created this line for transportation reasons. The observatory was also established at about this time. Therefore, the country decided to draw this imaginary line. However, it was moved later because it was getting in the way. Now, the meridian goes through several countries including Spain, Mali and Niger to name a few.