The stars which they should bet on is ย D) a star of about 8% the mass of our Sun.
This refers to the astronomical object which is very far away in the galaxy and and of which the closest star to the Earth is in fact the Sun.
With this in mind, we can see that the students are making bets about the time different stars will take to evolve and want to know which star will become a red giant first so they should bet on a star of about 8% the mass of our Sun.
Read more about stars here:
https://brainly.com/question/25821071