To start one difference between the two is that a scientific experiment is meant to be repeated and to be formed into a theory and/or a scientific law. Scientific experiments also use different types of data, for instance, you could be recording how much a plant grows in a month, in an experiment you would focus on the types of soil being used. In an investigation you would observe how tall the plant actually grew.
The first option, collapsed in on itself.
The star's core mass becomes so dense that the resulting gravity implodes the star.
Interesting enough, the third option is kindof true too...some large and tenacious black holes that absorb other stars will form incredibly bright accretion disks around their perimeter before filling absorbing the star.
Answer:
One ring is present.
Explanation:
The degree of unsaturation or double bond equivalents(DBE) can be determined by using a formula. This formula gives us the number of rings and / pi bonds.
As mentioned in the problem the number of pi bond is one so if we calculate the DBE this will give us the number of rings by subtracting one from DBE.

Where
C = number of carbon atoms
X = number of halogens
N = number of nitrogen
H = number of hydrogen

Thus the number of rings will be:

Just do 6.5 * (6.02 * 10^23)
Sorry I don’t have a calculator on me
Type that into the calculator to get your answer